OPERATING INSTRUCTION MANUAL FOR THE CS4-10V MAGNET POWER SUPPLY

Summary

This operating instruction manual details the installation, setup, operation, and computer interfacing for the Cryomagnetics CS4-10V superconducting magnet power supply. It provides specifications, menu navigation, command references for RS-232 and IEEE-488.2, calibration procedures, and details on the optional superconducting shim power supply upgrade.

Title Page

OPERATING INSTRUCTION MANUAL FOR THE CS4-10V MAGNET POWER SUPPLY Rev. 3.1 – Sept. 10, 2004

CRYOMAGNETICS, INC. INNOVATIVE SUPERCONDUCTING MAGNET SOLUTIONS 1006 Alvin Weinberg Drive Oak Ridge, Tennessee 37830 Phone: (865) 482-9551 Fax: (865) 483-1253 Web: http://www.cryomagnetics.com

WARNING! DO NOT ATTEMPT TO OPERATE THIS EQUIPMENT BEFORE YOU HAVE THOROUGHLY READ THIS INSTRUCTION MANUAL.

Declaration of Conformity - CS4-10V/100

CE MANUFACTURER’S DECLARATION OF CONFORMITY According to ISO / IEC Guide 22 and EN45014

Manufacturer’s Name: Cryomagnetics, Inc. Manufacturer’s Address: 1006 Alvin Weinberg Drive, Oak Ridge, TN 37830

Declares, the product Product Name: Superconducting Magnet Power Supply Model Number: CS4-10V/100 Product Options: All Options

Conforms to the following Product Specifications: Safety: EN61010-1, 1993, Amendment 2; EN61326 EMC: EN55011 Conducted Emissions, EN55011 Radiated Emissions, EN61000-3-2 Harmonics, EN61000-3-3 Flicker, EN61000-4-2 ESD Air Discharge (1kv, 2kv, 4kV), EN61000-4-2 ESD Contact Discharge (2kv, 4kV, 8kV), EN61000-4-3 Radiated Immunity 10V/m, EN61000-4-4 EFT 500V, 1kV, 2kV, IEC 1000-4-5:1995 Surge 500V, 1kV L-L / 500V, 1kV, 2kV L-G, EN61000-4-6 Conducted Immunity 10V rms, EN61000-4-8 Power Frequency Magnetic Field, EN61000-4-11 Voltage Dips and Interrupts

Application of Council Directives: The product complies with the requirements of the Low Voltage Directive 73/23/EEC as amended by 93/68/EEC and the EMC Directive 89/336/EEC as amended by 93/68/EEC.

D.M. Coffey, President Cryomagnetics, Inc Oak Ridge Tennessee March 31, 2003

Declaration of Conformity - CS4-10V/60

CE MANUFACTURER’S DECLARATION OF CONFORMITY According to ISO / IEC Guide 22 and EN45014

Manufacturer’s Name: Cryomagnetics, Inc. Manufacturer’s Address: 1006 Alvin Weinberg Drive, Oak Ridge, TN 37830

Declares, the product Product Name: Superconducting Magnet Power Supply Model Number: CS4-10V/60 Product Options: All Options

Application of Council Directives: The product complies with the requirements of the Low Voltage Directive 73/23/EEC as amended by 93/68/EEC and the EMC Directive 89/336/EEC as amended by 93/68/EEC.

D.M. Coffey, President Cryomagnetics, Inc Oak Ridge Tennessee October 18, 2003

TABLE OF CONTENTS

Introduction - 1 1.1 Description - 1 1.2 Features - 2 1.3 Specifications - 4
Installation and Setup - 5 2.1. Line Voltage and Fuses - 5 2.2. Mounting - 5 2.3. Environment - 5 2.4. Terminal Strip Connections - 6 2.5. Power Output Terminals - 7
Magnet Setup and Operation - 9 3.1. Setting Magnet Parameters - 9 3.2. Setting Charge Rates - 9 3.3. Setting Limits - 10 3.4. Energizing the Magnet - 10 3.5. Discharging the Magnet - 11 3.6. Power Fail Mode - 11 3.7. Magnet Quench - 12
Displays and Menus - 13 4.1. Normal Operating Display - 13 4.1.1. Operating Mode - 14 4.1.2. Sweep Mode - 14 4.1.3. Local / Remote - 14 4.1.4. Output Current - 14 4.1.5. Display Units - 14 4.1.6. Output Voltage - 14 4.1.7. Magnet Current - 15 4.1.8. Magnet Voltage - 15 4.1.9. Upper Sweep Limit - 15 4.1.10. Lower Sweep Limit - 15 4.1.11. Output Voltage Limit - 15 4.1.12. Persistent Switch Heater Status - 15 4.1.13. External Control Indicator - 15 4.2. Keypad Operation - 15 4.3. Menus - 16 4.3.1. Main Menu - 17 4.3.2. Limits Menu - 18 4.3.2.1. Upper and Lower Current Limits - 19 4.3.2.2. Voltage Limit - 19 4.3.3. Rates Menu - 19 4.3.3.1. Current Ranges - 19 4.3.3.2. Sweep Rates - 19 4.3.3.3. Fast Mode - 20 4.3.4. Magnet Menu - 20 4.3.4.1. Units - 20 4.3.4.2. Persistent Mode Current - 20 4.3.4.3. Max Current - 21 4.3.4.4. Field-to-Current Ratio - 21 4.3.4.5. Persistent Switch Heater Current - 21 4.3.5. Setup Menu - 21 4.3.5.1. Control Source Menu - 22 4.3.5.1.1. Current Limit Source - 22 4.3.5.1.2. Voltage Limit Source - 22 4.3.5.1.3. Charge Rate Source - 22 4.3.5.2. Computer Interface Menu - 23 4.3.5.2.1. Selected Interface - 23 4.3.5.2.2. RS-232 Baud Rate - 23 4.3.5.2.3. GPIB Device ID - 23 4.3.5.2.4. Serial Number - 23 4.3.5.3. Quench Detect - 23 4.3.6. Calibrate Menu - 24 5 Interfacing - 25 5.1. RS-232 Computer Interface - 25 5.2. IEEE-488.2 Computer Interface (Optional) - 26
Theory of Operation - 27 6.1 Circuit Description - 27
Limited Warranty Policy - 29 Appendix A. - Factory Calibrations, Installed Options and Certification - 31 Appendix B. - Computer Interface Command Reference - 33 Appendix C. - Calibration Procedures - 51 C.1. Calibration Menu - 51 C.2. Analog Input Calibration Menu - 51 C.2.1. Set Current Calibration (±Iset) - 52 C.2.1.1. Current Limit Offset - 52 C.2.1.2. Current Limit Gain - 52 C.2.2. Set Voltage Calibration (±Vset) - 53 C.2.2.1. Voltage Limit (Charge Rate) Offset - 53 C.2.2.2. Voltage Limit (Charge Rate) Gain - 53 C.2.3. Magnet Voltage Calibration (±Mag.Vin.) - 54 C.2.3.1. Magnet Voltage Offset - 54 C.2.3.2. Magnet Voltage Gain - 54 C.1. Analog Output Calibration Menu - 55 C.3.1. Analog Output Current and Voltage Calibrations (±Iout & ±Vout) - 55 C.3.2. Analog Output Magnet Voltage Calibration (±Mag.Vout) - 56 C.4. Power Output Calibration Menu - 56 C.4.1. Power Output Gain and Offset - 56 C.4.2. DAC Offset - 57 C.4.3. Swamp Resistor - 58 C.5. Power PID Calibration - 59 Appendix D. - Shim Supply Option - 61 D.1. Overview - 61 D.2. Shim Option Description - 62 D.3. Setup - 64 D.3.1. MANUAL Mode - 64 D.3.2. SHIM Mode - 65 D.3.3. Selection Menu - 66 D.3.4. Setup Menu - 66 D.3.5. Hardware Connections - 67 D.4. Operation - 68 D.4.1. Energizing Shims - 68 D.4.2. Discharging Shims - 69

Symbols and Abbreviations Warning – Danger of electrical shock A: Amperes °C: degrees centigrade °F: degrees Fahrenheit Hz: Hertz kg: kilograms kG: kilogauss mA: milliamperes mV: millivolts T: Tesla

1. Introduction

Introduction This section provides an introduction to the Cryomagnetics model CS4-10V/100 Superconducting Magnet Power Supply. Features and capabilities of the instrument are outlined and performance specifications are described.

1.1. Description The CS-4 Superconducting Magnet Power Supply is an advanced instrument designed specifically for powering superconducting magnets. It is a true four-quadrant power supply – meaning it is capable of operating with positive current / positive voltage (sourcing power), positive current / negative voltage (sinking power), negative current / positive voltage (sinking power), and negative current / negative voltage (sourcing power). The supply allows the user to generate smooth sweeps through zero current for performing hysteresis loop experiments or other research requiring smooth magnetic field reversal.

The CS-4 is capable of delivering up to ±10 volts of output voltage and up to 100 amps of output current, depending upon which CS-4 is used. An easy-to-use menu system is provided to allow the operator to set the supply up using the parameters of his/her particular magnet. Most of the supply operating parameters are available through the standard RS-232 computer interface and/or an optional IEEE-488 interface.

Power supplies used for energizing superconducting magnets have unique requirements placed upon them. The supplies are used to source energy to magnets which can have a wide range of inductance (mH to thousands of henries). In addition, the magnet load can range from a nearly pure resistance to a nearly pure inductance – and everything in between. This places demands on the supply that are far beyond what a typical power supply used for bench top electronics would see. The supply will experience the challenges of sinking energy when a magnet is discharging every day. At the same time, the potential exists for either the magnet or power supply to be damaged in the event of a power failure or magnet quench. The CS-4’s advanced circuitry enables it to take virtually any scenario encountered in superconducting magnet operation in stride.

The quiet switch-mode design of the CS-4 makes it a low noise, highly efficient supply – and one that is proven stable even on the most sensitive superconducting magnets. Versatile programmability allows the user to specify several different sweep rates for different current ranges of the magnet – making it possible to sweep a magnet slower in a particular range if it is more sensitive there without user intervention.

1.2. Features

1.2. Features The CS-4 has a wide range of features available:

• True Four-Quadrant Operation. The supply can provide positive or negative output current along with either polarity voltage. This gives it the ability to smoothly sweep through zero current without the need for current reversing switches or pauses. • User – Friendly Menus. The CS-4 has intuitive menus to display and enter operating parameters. It can be set up in a matter of minutes and changes during daily operation are simple and quick. • Easy to Read Display. The high quality vacuum fluorescent graphic display gives the operator essential information at a glance, even from across the lab. • ± 10 Volt/± 100A High Stability Output. The CS-4 provides quiet, stable output power thanks to its low noise switch-mode design and precision current monitoring and control circuits. • Power Fail Magnet Discharge. Should a power failure occur during operation of the magnet, the supply converts to a “Power Fail” mode wherein it draws its power from the discharging magnet rather than the AC line. When “Power Fail” mode is entered, the display is brought back on-line and the user can monitor the discharge of the magnet. If power is restored, the user can intervene to stop the discharge and re-energize the magnet if desired. “Power Fail” mode is a convenient feature of the CS-4 since it enables the user to simply turn OFF the power switch for the unit at the end of the day. The CS-4 will safely and automatically restore the display and discharge the magnet – quietly going to sleep when it’s done. • Independent Upper and Lower Current Limit Setpoints. Independent current limits allows sweeping between two setpoints without having to re-enter the menu and constantly change limit settings. • PID-Controlled Sweeping. A PID inside the power supply’s control circuits allows smooth sweeping between setpoints without the need for or dependence on voltage taps across the magnet. • Changeable Settings During Sweep. The menu system can be entered at virtually any time during operation of the supply to change parameters. While in the menu, the top line of the display continues to update the user as to the status of the supply/magnet. • Computer Interfacing. A versatile RS-232 interface is standard and an IEEE-488 interface is optional. Through either interface, a comprehensive set of monitor and control commands is available. The IEEE-488 interface conforms to the IEEE-488.2-1992 standard. • LabVIEW™ drivers. Virtual Instrument drivers compatible with National Instruments LabVIEW™ are available for Cryomagnetics’ instrumentation through Cryomagnetics’ website. • Analog Input Programming Interface. The user can provide analog signals to the CS-4 if desired which will be interpreted as current limit, voltage limit, and/or charge rate. • Analog Output Monitor Interface. Analog output signals are provided to allow the user to connect the supply to a chart recorder or other monitoring instrumentation. Analog signals proportional to magnet current, magnet voltage and power supply voltage are provided. • Built-in Persistent Switch Heater Supply. A power supply for energizing a persistent switch is built into the CS-4. • Remote Shut-down Input. A signal can be provided by the user to the CS-4 which commands it to discharge (Zero) the magnet. This can be used to lock out operation of the magnet when helium gets too low or when some other user-defined event occurs. • Quench Detection and Protection. The CS-4 is fully protected from damage due to quench. In addition, if a quench is detected the CS-4 will give an audible and visual indication of the quench. The current at which the quench occurred will be displayed on the unit’s front panel. Since quench detection is activated on observed current transients, it must be disabled if automatic recovery is desired from abnormal conditions such as those encountered in several of the CE qualification tests. These tests include electrical fast transient and electrostatic discharge.

1.3. Specifications

DC Output: 0 to ± 100 A (Current), 0 to ± 10 V (Voltage) Ripple and noise: 20 uA rms (Current), 10 mV rms @ 100A (Voltage) Stability (drift) at 25 ± 1C: ± 0.005% Imax (Current), ± 0.01% Vmax (Voltage) Display Resolution: 1 mA (Current), 10 mV (Voltage) Display Update Rate: ~ 500ms Intervals. Output Current Setability: 1 mA (Current), 40 mV (Voltage) Sweep Rate Resolution: 0.1 mA/sec via Front Panel or 20uA/sec via Remote Interface. Source effect (line regulation for any line change within the rated line voltage): 0.005% Imax (Current), 0.05% Vmax (Voltage) Load effect (load regulation for a load change equal to max. voltage in constant current mode or max. current in constant voltage mode): 0.01% Imax (Current), 0.01% Imax (Voltage) Output Protection: Protected from damage due to quench. AC Input: 220-230V a.c., 50-60 Hz, 10A Fuses: 10A, 250V a.c., slow blow Operating Temperature: 15 °C to 35 °C Relative Humidity: 10% to 95%, noncondensing Overtemperature Protection: Unit will shutdown if internal heatsink temperature exceeds 80 °C. Dimensions: 483 mm W X 179 mm H X 585 mm D Weight: 23.6 kG (52 lbs) RS-232 interface: Standard IEEE-488 interface: Optional, To IEEE-488.2-1992 Standard. Analog Programming Inputs: 0-10V Std, Option for 0-1V, ±10V, 4-20mA Analog Programming Outputs: 0-10V Std, Option for 0-1V, ±10V, 4-20mA

The CS4-10V/100 is designed to operate per the specifications in this table and the instructions provided in this manual. Other use may impair the safety protections provided by the equipment.

2. Installation and Setup

Installation and Setup The following section outlines information concerning the initial unpacking, installation and setup of the CS-4 supply. As with any equipment purchase, the user is strongly encouraged to inspect the power supply for shipping damage immediately upon receipt. Proper power and ground connections should be made using the appropriate codes and practices. Should the CS-4 require return to the factory due to shipping damage or for servicing, contact Cryomagnetics or an authorized service representative for instructions and a return authorization number.

The CS-4 is delivered to you fully tested, calibrated, and ready to operate. This includes configuring appropriate setup values if the supply is purchased with a magnet system.

2.1. Line Voltage and Fuses The CS-4 is fused for operation using 220-230 V a.c., 50-60 Hz input power. Two 10 amp fuses are required for this input voltage configuration. The fuses are located in the power entry module. The power supply has been tested per EN61010 over the voltage range of 198-253 V a.c. Never replace the fuses with wires and never use ungrounded power cords for line power.

It is strongly recommended that AC power provided to the CS-4 be protected with a Ground Fault Interrupter (GFI) and a surge suppresser. If the unit is operating in an area subject to power failures or brownouts, the user may wish to install an Uninterruptible Power Supply (UPS) to minimize the chance of inadvertently discharging or quenching the magnet due to line effects.

2.2. Mounting The CS-4 is compatible with all standard 19-inch wide rack cabinets. Due to the instrument’s weight, it is recommended that rails be located beneath the supply to prevent bending of the supply mounting brackets. Adequate ventilation is essential to the CS-4. An unobstructed air path should be available at the ventilation slots in the rear and side panels of the instrument and at the fan outlet to avoid overheating.

2.3. Environment The CS-4 is designed for operation in free air, non-condensing atmospheres within a temperature range of 15 to 35C (59 to 95F). It has been designed primarily for laboratory use – so harsh environments of dust or corrosive materials could result in eventual damage. A filtered enclosure is recommended for operation under these conditions.

2.4. Terminal Strip Connections The rear panel terminal strip of the CS-4 provides service for all analog input and output signals for the CS-4. The terminal strip is shown in Figure 2.1 and Table 2.1 outlines the definition and function of each terminal pair. A cover is provided to prevent electrostatic discharge damage to the electrical connections.

Figure 2.1 Rear Panel Terminal Strip: Terminals 1 through 18.

Table 2.1 Terminal Functions: 1 Ground: Ground connection for output cable shields 2 Ground: Ground connection for I/O cable shields 3 Shutdown -: Automatic Power Supply Shutdown - Input Signal from User to CS-4 (Used for magnet discharge on low helium) 4 Shutdown +: Leave open if not in use. 5 Mag.Vout -: Magnet Voltage Monitor – Output Signal Generated by CS-4 6 Mag.Vout + 7 Vout -: Power Supply Output Voltage – Output Signal Generated by CS-4 (Isolated from true supply output) 8 Vout + 9 Iout -: Power Supply Output Current – Output Signal Generated by CS-4 (Isolated from true supply output) 10 Iout + 11 Vset -: Power Supply Voltage Limit / Rate Set - User Generated Analog Programming Input to CS-4 12 Vset + 13 Iset -: Power Supply Current Limit Set - User Generated Analog Programming Input to CS-4 14 Iset + 15 Mag.Vin -: Magnet Voltage Taps – Input Signal to CS-4 from Magnet (Not required for operation). 16 Mag.Vin + 17 Per.Sw. -: Persistent Switch Heater Power Supply Output 18 Per.Sw. +

Before making connections to the rear panel terminal strip, make sure the power to the CS-4 is OFF. Shield cables must be used with shields connected to terminal 2 for CE compliance. Make all connections using the appropriate wire size. The terminal strip is designed to accept AWG 24 – 12 (0.2 – 2.5 mm2 stranded or 0.2 – 0.4 mm2 solid) conductor. The ends should be stripped bare 7mm. All connections should be isolated from instrument ground and from each other.

2.5. Power Output Terminals The high current output terminals are located on the rear panel and are labeled – OUT and + OUT. Before attaching the terminals to the magnet power leads, make sure the CS-4 power is OFF. Care should be taken in attaching power leads for the magnet to insure solid contact is made using a ¼-20 bolt with nut to each terminal. Although quench protection is built into the CS-4 to prevent the occurrence of high voltages, the magnet leads should NEVER be disconnected when current is present. Potentially lethal voltage can easily occur due to the high inductance of superconducting magnets.

CAUTION – RISK OF ELECTRIC SHOCK

Note: Ferrite beads (Fair-Rite P/N 0444177081) must be installed on the output cables for compliance with CE standards for RF conducted immunity. Cables must be shielded with shields connected to terminal 1 of the terminal block.

2.6. Maintenance The CS-4 should be inspected periodically to verify that all connections are secure, fans operate properly, and that the ventilation openings are clear.

If cleaning is required, disconnect the power cord and clean the unit with a soft cloth dampened with water.

The CS-4 does not contain user serviceable parts. If repairs should be required, contact the factory for a repair authorization number, and return to the factory for service to ensure the integrity of the unit is maintained.

3. Magnet Setup and Operation

Magnet Setup and Operation The CS-4 is designed specifically for operation with superconducting magnets. Before using the supply to energize a magnet; however, certain parameters specific to the superconducting magnet being used, the charge rate(s) desired during field sweep, and the operating current limit(s) should be set through the menu system. The following procedure is recommended.

3.1. Setting Magnet Parameters The first thing the user should set up are the magnet parameters. To set these up, press the [Menu] key on the front panel. Use the arrow keys to select <Magnet> and press [Enter]. The display will indicate the Magnet Parameters. If the magnet to be energized is currently at zero field, the Persistent Mode Current should be set to 0.000A. If the magnet is already in persistent mode at some other known current, this current can be entered. Be sure the polarity of the magnet current is entered correctly.

The maximum safe operating current for the magnet should be entered in the Max Current parameter position. The supply will not allow output current to exceed this value. Should the user attempt to enter a Current Limit setting above this value (in the Limits menu), the supply will set the limit to the Max Current value observing polarity.

The field-to-current ratio of the magnet may be entered in the Magnet Parameters setup if desired. The CS-4 only uses this parameter if the user wants the display to indicate output current in terms of magnetic field units (kilogauss or Tesla) rather than amps. Consequently setting this parameter is not essential.

If the magnet to be energized is equipped with a persistent mode switch, the heater current necessary to activate it should be entered in the Switch Heater Current Field. The persistent switch heater power supply is capable of up to 100 mA of output current.

3.2. Setting Charge Rates The charge rate(s) for energizing the magnet should be entered through the Rates menu item in the main menu. The CS-4 allows the user to set up to three different charge rates to be used in three current ranges. This allows the user to specify a slower rate for a magnet when it is near its maximum rated field.

From the main menu, use the arrow keys to select <Rates> and press [Enter]. Using the inductance of the magnet as a guide, set the desired rates keeping in mind that the best (smoothest) sweeps of the magnet are achieved when voltage limit is not exceeded. The charging voltage of the magnet is computed by V = L di/dt, where the value of di/dt is the sweep rate in amperes per second indicated in the Rates menu.

Once the rates and their respective current ranges have been set, press [Menu] and [Enter] to accept the changes (or [Esc] to abort and ignore all changes).

3.3. Setting Limits The desired operating current for the magnet is set in the Limits menu item in the main menu. The CS-4 allows the user to enter two different limits – an upper and a lower – to enable smooth sweeps between two points. Either or both of the upper and lower current limits may be positive or negative current values as long as the upper is more positive than the lower.

From the main menu, use the arrow keys to select <Limits> and press [Enter]. Use the arrow keys to select the appropriate current limit and then enter the desired value. If changes to the voltage limit are desired, this can be entered now, too.

Once the desired current limits have been set, press [Menu] and [Enter] to accept the changes (or [Esc] to abort and ignore the changes).

3.4. Energizing the Magnet Once the magnet parameters, charge rates, and limits have been set, the supply is ready to energize the magnet. From the main operating menu, energize the persistent switch heater supply by pressing the [PSHtr] key. The CS-4 will ask for confirmation before energizing the heater. Confirm that the heater is to be turned on by pressing [Enter] (or [Esc] to abort energizing the persistent switch heater). Wait for a few seconds or whatever time is required by the magnet’s persistent switch before beginning the field sweep.

Press the up arrow key [↑] to begin energizing the magnet in the direction of the upper current limit. Alternatively, the operator can press the down arrow key [↓] to begin energizing the magnet in the direction of the lower current limit. Once the appropriate current limit is reached, the CS-4 will hold that current.

To place the magnet into persistent mode, turn off the persistent switch heater supply by pressing the [PSHtr] key. The CS-4 will ask for confirmation before turning off the heater. Press [Enter] to confirm (or [Esc] to abort). Wait a few seconds or whatever time is required by the magnet’s persistent switch before zeroing the current in the leads.

Once the magnet is in persistent mode, the current in the leads may be brought back to zero by pressing the [Zero] key.

IMPORTANT Be sure to zero the supply by pressing the [Zero] key. Pressing the down arrow key [↓] will result in the supply sweeping to the lower current limit rather than to zero.

Watch the magnet voltage while the supply begins to sweep toward zero to verify that the magnet has indeed entered persistent mode. If no voltage is detected, press [Shift-Zero] to bring the supply back to zero output current more quickly. When the supply reaches zero output current, it automatically switches to Standby mode.

3.5. Discharging the Magnet To discharge a magnet that is in persistent mode, press the [Shift-↑↑] or [Shift-↓↓] to quickly bring the supply output current back to the current left in the magnet. Be sure to bring the current back in the proper polarity as was left in the magnet.

When current limit is reached, the supply will stabilize and hold that current. From the main operating menu, energize the persistent switch heater supply by pressing the [PSHtr] key. The CS-4 will ask for confirmation before energizing the heater. Confirm that the heater is to be turned on by pressing [Enter] (or [Esc] to abort energizing the persistent switch heater). Wait for a few seconds (or whatever time is required by the magnet’s persistent switch) before beginning the field sweep.

Once the persistent switch is warm, sweep the magnet current back to zero by pressing the [Zero] key. Watch the magnet voltage to verify that the magnet is beginning to discharge. When the supply reaches zero output current, it will automatically change to Standby mode. Turn off the persistent switch heater by pressing the [PSHtr] key and [Enter] to confirm.

To sweep to the opposite current limit rather than zero, press the appropriate [↑] or [↓] key rather than the [Zero] key. The supply will smoothly sweep through zero and on to the other current limit.

3.6. Power Fail Mode Should there be a loss of line power during energizing or discharging of the superconducting magnet, the CS-4 will automatically switch to Power Fail Mode. In Power Fail Mode, the instrument draws the power needed to maintain itself from the superconducting magnet rather than the line.

In the event of a power failure, the CS-4 display will momentarily blank, then the normal sign-on message will appear. The instrument reinitializes itself and then restores the Operating mode display. The magnet discharges at approximately 7.5 volts – the minimum necessary to maintain CS-4 operation. Current in the leads is accurately displayed as the magnet discharges. It is not possible to abort the discharge while line power is absent because this would instantly result in the CS-4 losing the power it needs to remain active.

If line power is restored, the CS-4 will continue to discharge the magnet (Zeroing↑ or ↓) unless the user intervenes. Upon return of line power, the supply switches back to normal line powered operation and simultaneously displays a message indicating that line power has been restored. The supply will give a triple-beep every 10 seconds to alert the user that line power has been restored. Pressing any key results in clearing the line fault indication and the beeping stops. The magnet may be energized again immediately if desired – complete magnet discharge is not necessary.

3.7. Magnet Quench The CS-4 has magnet quench detection built-in. In the event a magnet quench is detected, a message indicating the quench has occurred will be displayed and the supply will switch to Standby mode. The supply will also indicate the current at which it was operating when the quench occurred. The quench indication is cleared by pressing [Shift-Enter].

4. Displays and Menus

Displays and Menus Setup and operation of the CS-4 may be performed either through the front panel keypad and simple menu instructions or through a remote computer interface (RS-232 or IEEE-488.2). Calibration and magnet-specific setup parameters are only supported through the front panel keypad. The following sections contain descriptions of how to configure and operate the CS-4 through the front panel.

Before connecting a magnet or other cabling to the CS-4, connect the power cord provided with your CS-4 to an appropriate power source. Power the instrument ON and familiarize yourself with the display and keypad.

4.1. Normal Operating Display The normal operating display shown in Figure 4.1 provides the information necessary to quickly determine the power supply output and operating mode.

Figure 4.1 - Normal Operating Display Fields: 1 Operating Mode (MANUAL) 2 Sweep Mode (STANDBY) 3 Local/Remote (Lcl) 4 Output Current (+0.000A) 5 Display Units (A) 6 Output Voltage (+0.00V) 7 Magnet Current (MAGNET: +0.000A) 8 Magnet Voltage (+0.00V) 9 Upper Sweep Limit (+20.000A) 10 Lower Sweep Limit (-5.000A) 11 Output Voltage Limit (±5.00V) 12 Persistent Switch Heater (P.S. HEATER: OFF) 13 External Control Indicator ((Ext))

4.1.1. Operating Mode The Operating mode field (1) will display the prior operating mode at power up. MANUAL mode is the normal operating mode. SHIM mode is available if the shim option is installed.

4.1.2. Sweep Mode The Sweep Mode field (2) indicates the present supply activity. STANDBY indicates that the power supply output module is disabled and not developing power. SWEEP ↑ indicates that the supply output current is being swept in the direction of the upper sweep limit. SWEEP ↓ indicates that the supply output current is being swept in the direction of the lower sweep limit. PAUSED indicates that the sweep function is not active, and that the supply is maintaining a prescribed output current. Zeroing ↑ or Zeroing ↓ indicates the supply is discharging.

When the Sweep Mode is SWEEP ↑ or SWEEP ↓, the sweep will continue until the respective upper or lower current limit is reached. When Zeroing, the Sweep Mode of the supply will automatically change to STANDBY when zero current is reached.

4.1.3. Local / Remote The Lcl indicator (3) shows that operator has pressed the Local button, and that the remote interfaces (RS-232 or GPIB) cannot control the supply until the operator presses the Local button again. The Rem indicator shows that a remote interface is controlling the supply, and that all buttons except the Local button are disabled.

4.1.4. Output Current The supply output current (4) is displayed in selected units, and is updated about twice a second.

4.1.5. Display Units The operator may select amps, kilogauss, or Tesla to display the output current (5).

4.1.6. Output Voltage The output voltage (6) is displayed in volts and is updated about twice a second.

4.1.7. Magnet Current The magnet current (7) is displayed in the selected units. The magnet current tracks the supply output current if the persistent switch heater is on. If the persistent switch heater is off, the magnet current will reflect the power supply output current at the time the persistent switch heater was turned off. The magnet current will show zero if a quench is detected.

4.1.8. Magnet Voltage The magnet voltage (8) is displayed if magnet taps are connected to magnet voltage analog inputs (±Mag.Vin., terminals 15 & 16 on the rear panel terminal strip).

4.1.9. Upper Sweep Limit The upper sweep limit (9) displays the current limit that will be used if the sweep up function is activated.

4.1.10. Lower Sweep Limit The lower sweep limit (10) displays the current limit that will be used if the sweep down function is activated.

4.1.11. Output Voltage Limit The output voltage limit (11) displays the maximum voltage that the supply is programmed to output.

4.1.12. Persistent Switch Heater The persistent switch heater status field (12) will display ON or OFF.

4.1.13. External Control Indicator The external control indicator field (13) will read “Ext” if the current limit, voltage limit, or sweep rate is set to Analog Input in the Control Source Setup Menu. If all are set to Programmed the “Ext” indicator will not be displayed.

4.2. Keypad Operation The keypad layout is shown in Figure 4.2. The [Mode], [PSHtr], and [Local] keys may only be used when the normal operating display is visible (Menu system inactive.) The remaining keys are used in both operating and menu modes. Keypad buttons include: Menu, Mode, PSHtr, Arrow keys (Up/Down/Left/Right, Fast Up/Down [Shift-↑↑ / Shift-↓↓]), Zero / Fast Zero, Esc, Local, ±, Shift, Numeric digits (0-9), Decimal (.), Enter.

A Select/Edit indicator is displayed at the end of the second line in the Menu system (see (6) in Figure 4.4). When Select is shown, the arrow keys can be used to move the highlight to the field to be selected. When Edit is shown, the selected field or entry position is flashed to indicate the item that will be affected when a key is pressed. A field is selected by pressing the [Enter] button when the field is highlighted. Once in Edit mode, the field contents may be changed by pressing a right or left arrow key (for text fields), or entering the value directly on the numeric keypad (for numeric fields). A numeric field may be cleared by pressing the [Zero] key. When the desired changes have been made the [Enter] button is pressed to accept the changes. The [Esc] button may be pressed to avoid making a change.

4.3. Menus The CS-4 menu system implements one or two levels of ‘Undo’ depending on how it is used. If a submenu is exited by pressing the [Esc] button after changes have been entered, a prompt is issued to “Press <Esc> to abort changes or <Enter> accept changes”. If [Enter] is pressed the changes are retained, but the changes are not implemented until the menu system is exited. When [Menu] is pressed in the menu system, the abort/accept prompt is displayed again, and if [Enter] is pressed, the changes are made. If [Esc] is pressed, any changes made in the menu system are forgotten. Note that [Esc] will back up one level in the menu system, but pressing [Menu] will return directly to the operating display.

Figure 4.3 shows the menu organization:

Main Menu (4.3.1)
- Limits Menu (4.3.2)
- Rates Menu (4.3.3)
- Magnet Menu (4.3.4)
- Setup Menu (4.3.5)
  - Control Source (4.3.5.1)
  - Computer Interface (4.3.5.2)
  - Quench Detect (4.3.5.3)
  - Shim Control (4.3.5.4)
- Calibrate Menu (Appendix C.1)
  - Analog Inputs (Appendix C.2)
  - Analog Outputs (Appendix C.3)
  - Power Output (Appendix C.4)
  - Power PID (Appendix C.5)

4.3.1. Main Menu Pressing [MENU] when the operating display is active will cause the Main Menu to be displayed. Pressing [MENU] again or [Esc] returns the instrument to the operating display. Be aware that some computer interface commands are not available while the menu system is active (see Appendix B).

Figure 4.4 - Main Menu layout: MANUAL STANDBY +0.000A +0.00V Lcl Main Menu Select Limits Rates Magnet Setup Calibrate

4.3.2. Limits Menu The Limits menu, shown in Figure 4.5, is used to set the sweep limits and voltage limit when the control source in the Setup menu is set to Programmed. The values are not used when the control source is set to Analog Input. Figure 4.5 layout: MANUAL STANDBY +0.000A +0.00V Lcl Limits Menu Select Upper Current Limit +20.000A Lower Current Limit -5.000A Voltage Limit ±5.00V

4.3.2.1. Upper and Lower Current Limits In the SWEEP ↑ mode the current will sweep at the prescribed rate until the upper current limit is reached, and in the SWEEP ↓ mode the lower current limit will be used. If the menu is entered and the upper limit is set to a value lower than the present current, the current will be increased or decreased as required to reach the new upper limit when the menu is exited.

4.3.2.2. Voltage Limit The voltage limit is used to set the maximum or minimum output voltage that will appear at the power supply output terminals during charge or discharge. Note that the voltage at the magnet will be either more or less due to the direction of current in the current leads and the lead resistance.

4.3.3. Rates Menu The Rates menu, shown in Figure 4.6, is used to set the sweep rates when the control source in the Setup menu is set to Programmed. The values are not used when the control source is set to Analog Input. Figure 4.6 layout: MANUAL STANDBY +0.000A +0.00V Lcl Rates Menu Select Current Range Sweep Rate Range 1 0.000A TO 60.000A 0.350A/S Range 2 60.000A TO 85.000A 0.250A/S Range 3 85.000A TO 100.000A 0.125A/S Fast mode: 10.000A/S

4.3.3.1. Current Ranges Three current ranges may be defined by setting the upper current limits for Range 1 and Range 2. Range 3 is set from the end of Range 2 to the supply output capacity.

4.3.3.2. Sweep Rates Sweep rates may be set for each current range. This allows sweep rates to be automatically reduced at high fields and increased at low fields if desired.

4.3.3.3. Fast Mode Fast mode sweep rate is used when sweep up fast [Shift-↑↑], sweep down fast [Shift-↓↓], or [Shift-Fast Zero] is selected. These modes are selected by holding the shift key and pressing the up arrow, down arrow, or zero button.

4.3.4. Magnet Menu The Magnet menu should be the first menu configured when preparing the supply for use since the Max Current parameter is used in the Limits and Rates menus. Figure 4.7 layout: MANUAL STANDBY +0.000A +0.00V Lcl Magnet Parameters Select Units: Amps Persistent Mode Current: 0.000A Max Current: 20.000A Field-to-Current Ratio: 1.0000kG/A Switch Heater Current: 40mA

4.3.4.1. Units The Units menu item allows the user to set the display units of the CS-4. Available options are Amps, kilogauss and Tesla. Once the system of units is selected, the CS-4 uses that system of units for displaying the output current, magnet current, and limits.

4.3.4.2. Persistent Mode Current Persistent mode current displays the present magnet current if it is in persistent mode and it was last used with the supply. If the magnet was placed in persistent mode using a different power supply, or if a magnet quenches while the power supply is turned off, this field may be preset or edited.

4.3.4.3. Max Current Max current sets the maximum current that may be set in the upper or lower current limits, and the maximum current that can be used to set the current ranges in the Rates menu. It would normally be set to the magnet’s maximum safe operating limit.

4.3.4.4. Field-to-Current Ratio The field-to-current ratio of the magnet is entered in units of kilogauss per ampere. It is used to display the magnetic field instead of output current if kilogauss or Tesla are selected in the Units menu item.

4.3.4.5. Persistent Switch Heater Current The persistent switch heater current can be set from 0 to 100 mA. The switch heater is not turned on until it is selected in the operating display or via a remote interface command.

4.3.5. Setup Menu The Setup menu is used to set the control source for the current and voltage limits and sweep rates, select computer interface parameters, enable or disable quench detect, and if the SHIM option is installed, it can be enabled or disabled, and the maximum shim current set. A submenu is invoked if Control Source or Computer Interface is selected. Figure 4.8 layout: MANUAL STANDBY +0.000A +0.00V Lcl Setup Parameters Select Control Source Computer Interface Quench Detect Enabled Shim Control Enabled Imax 30.0A

4.3.5.1. Control Source Menu The Control Source menu, shown in Figure 4.9, is used to set the control source for the current and voltage limits and sweep rates. Figure 4.9 layout: MANUAL STANDBY +0.000A +0.00V Lcl Control Source Select Current Limit Analog Input Voltage Limit Programmed Charge Rate Programmed

4.3.5.1.1. Current Limit Source The Current Limit is set in the Limits menu if Programmed is selected. When the control source is set to Analog Input, the output current limit follows the ± Iset analog inputs (terminals 13 & 14 on the rear panel terminal strip).

4.3.5.1.2. Voltage Limit Source The Voltage Limit is set in the Limits menu if Programmed is selected. When the control source is set to Analog Input, the voltage limit follows the ±Vset analog input (terminals 11 & 12 on the rear panel terminal strip). Either Voltage Limit or Charge Rate source may be set to programmed through the ±Vset analog input, but not both.

4.3.5.1.3. Charge Rate Source When the control source for Charge Rate (sweep rate) is set to “Programmed”, the sweep rates specified in the Rates menu is used. When the control source for Charge Rate is set to “Analog Input”, the charge rate follows the ±Vset analog input. Either Voltage Limit or Charge Rate source may be set to programmed through the ±Vset analog input, but not both.

4.3.5.2. Computer Interface Menu The Computer Interface menu, shown in Figure 4.10, is used to select the remote interface and to set the remote interface parameters. The menu also displays the unit serial number. Figure 4.10 layout: MANUAL STANDBY +0.000A +0.00V Lcl Computer Interface Select Selected Interface RS-232 RS-232 Baud Rate 9600 GPIB Device ID 1 Serial Number 2239

4.3.5.2.1. Selected Interface The selected interface field displays the computer interface to be selected the next time power is applied to the unit in accordance with the IEEE-488.2-1992 specification. The selection may be changed at any time without affecting the unit’s operation.

4.3.5.2.2. RS-232 Baud Rate The RS-232 baud rate may be set to 1200, 2400, 4800, or 9600 baud.

4.3.5.2.3. GPIB Device ID The GPIB device ID may be set from 0 to 31.

4.3.5.2.4. Serial Number The unit serial number is conveniently displayed for warranty purposes.

4.3.5.3. Quench Detect The supply monitors the output current when quench detect is enabled. If a rapid decrease is detected it assumes that a quench has occurred, and the supply is immediately placed in standby. At this point the supply stops delivering any current to the magnet system, which in turn protects the magnet’s quench protection system. The quench detect control allows this feature to be disabled.

4.3.5.4 Shim Control (Shim option only) The Shim Control allows the shim functions to be enabled or disabled by the operator, and to set the maximum output current allowed in shim mode. Imax should not normally be set above 30 A to avoid potential damage to the shim circuits in the magnet. Refer to Appendix D for shim operations.

4.3.6. Calibrate Menu The Calibration menu, shown in Figure 4.11, provides access to submenus used to calibrate the power supply functions. The supply is fully calibrated at the factory, and further calibration should not be required. Under the Calibrate menu item, the calibration of the CS-4’s analog inputs and outputs is performed, calibration of output current is made, and adjustment of the PID settings used during magnet sweep are entered. Appendix C outlines calibration procedures for the supply. Note that changing some settings could cause instabilities in your system, so care should be taken in changing calibrations. Refer to Appendix A for factory default settings for the supply. Figure 4.11 layout: MANUAL STANDBY +0.000A +0.00V Lcl Calibration Menu Select Analog Inputs Analog Outputs Power Output Power PID

5. Interfacing

Interfacing The CS-4 comes standard with an RS-232 computer interface. Front panel functions, except setup and calibration functions, may be accessed using the corresponding command string over the RS-232 port. In addition, an IEEE-488.2 port is available as an option. This port conforms to the IEEE-488.2-1992 standard.

5.1. RS-232 Computer Interface The RS-232 port is accessed through the DB-9F connector on the rear panel of the instrument. The interface is factory configured for 9600 baud, 8 data bits, 1 stop bit, no parity. Figure 5.0 indicates the proper pin designations for the port.

Figure 5.0 - RS-232 Port Connector Wiring: Pin 1, 4, 6, 7, 8, 9: N/C Pin 2: RS-232 Transmit Pin 3: RS-232 Receive Pin 5: Ground (View Facing Rear Panel Connector)

Commands available to the CS-4 operator over the RS-232 computer interface are given in Appendix B. The commands available through RS-232 are identical to those available through IEEE-488.2; however, some commands may be IEEE-488.2 specific and may not provide responses consistent with the RS-232 interface. The RS-232 command set includes Local, Remote, and RWLock which are not applicable to IEEE-488.2.

Command strings are normally limited to 60 characters when the RS-232 interface is used. A <RETURN> will be generated internally when any line longer than the maximum is encountered, and any valid commands in the received line prior to the internally generated <RETURN> will be processed. An output buffer of 62 characters is used although longer responses can be successfully generated. All remote commands are case insensitive, allowing upper or lower case to be used without affecting operation of the commands.

When the RS-232 interface is selected, all commands sent to the instrument will be echoed including the terminating ASCII <RETURN> character, followed by a <NEWLINE> character when command processing is complete.

5.2. IEEE-488.2 Computer Interface The CS-4 may have an optional IEEE-488.2 computer interface. The CS-4 implements SH1, AH1, T6, L4, SR1, RL1, PP0, DC1, DT0, C0, and E1 options. The commands are compliant with the IEEE-488.2 standard. The connector is identified on the rear panel of the instrument.

Reference: IEEE Standard Codes, Formats, Protocols, and Common Commands (IEEE Std 488.2-1992) provides a detailed description of the IEEE common commands (identifiable in the command list by the asterisk as the first character.)

The command list and structure is identical to the RS-232 command set except that Local, Remote, and RWLock functions are provided through the RL1 option. Reference Appendix B for a detailed description.

6. Theory of Operation & 7. Limited Warranty Policy

Theory of Operation The CS-4 is a 4 quadrant power supply with glitch free bi-directional output capability and programmable voltage limiting in both polarities.

6.1. CS-4 Circuit Description The CS-4 Power Supply is a 68HC11 microprocessor based unit. This microprocessor has built-in EEPROM that is used to hold factory calibration and configuration data, as well as user entered calibration and setup information. Consequently, it is not possible to simply change the processor with another 68HC11. The unit will not work properly with a new processor until it has been initialized by the factory.

The processor controls virtually all aspects of the CS-4 including the display, keypad, output power module, and the high stability, 24-bit analog-to-digital converter used to monitor analog input voltages.

Output current is set by a 16 bit digital-to-analog converter controlled by a software PID algorithm updated at a 200 millisecond interval. A 20 bit sigma-delta analog-to-digital converter is used to sense the output current. The programmable current sweep rate is digitally implemented in the PID algorithm.

The microprocessor, display, I/O, and fan operate from a DC-DC converter that allows magnet discharge to be safely monitored via the display or remote interface even if wall power fails.

The CS-4’s display is a bright, vacuum fluorescent unit having high contrast. It is capable of graphics and full alphanumerics and can clearly be read from a significant distance.

7.0. Limited Warranty Policy Cryomagnetics, Inc. warrants its products to be free from defects in materials and workmanship. This warranty shall be effective for one (1) year after the date of shipment from Cryomagnetics. Cryomagnetics reserves the right to elect to repair, replace, or give credit for the purchase price of any product subject to warranty adjustment. Return of all products for warranty adjustment shall be FOB Oak Ridge, TN, and must have prior authorization for such return from an authorized Cryomagnetics, Inc. representative.

This warranty shall not apply to any product which has been determined by Cryomagnetics, Inc. inspection to have become defective due to abuse, mishandling, accident, alteration, improper installation or other causes. Cryomagnetics, Inc. products are designed for use by knowledgeable, competent technical personnel.

In any event, the liability of Cryomagnetics, Inc. is strictly limited to the purchase price of the equipment supplied by Cryomagnetics, Inc. Cryomagnetics, Inc. shall not assume liability for any consequential damages associated with use or misuse of its equipment.

Appendix A - Factory Calibrations, Installed Options and Certification

Appendix A Factory Calibrations, Installed Options and Certification

Model: CS4-10V/100 Serial Number: Firmware Version: Options: GPIB

Analog Input Range (Gain, Offset, 0-1V, 0-10V, +-10V, 4-20mA):

Set Current
Set Voltage
Magnet Voltage

Analog Output Range (Gain, Offset, 0-1V, 0-10V, +-10V, 4-20mA):

Output Current
Output Voltage
Magnet Voltage

Power Output:

Output Gain
Output Offset
DAC Offset

PID Settings:

Proportional Gain
Integral Gain
Differential Gain

Notes: Certified: Date:

Appendix B - Computer Interface Command Reference

Appendix B Computer Interface Command Reference

Commands available over the computer interface are identified by availability. Commands that are available only when the operational display is active are noted as “Operate”, commands that require remote mode are noted as “Remote”. All queries and IEEE-488.2 specific commands are always available, regardless of whether the state is Local, Remote, or unassigned. Commands that are IEEE 488.2 specific can be recognized by an asterisk (*) as the first character. All command mnemonics that elicit a response from the instrument (referred to as queries) end with a question (?) character. The general command format is as follows: <subcommand1>;<subcommand2>;<subcommand3><RETURN> where a subcommand is formatted: <Command Mnemonic><SPACE><Parameter>

Example: *IDN?; UNITS T;UNITS?<RETURN> Responses to each subcommand are separated by semicolons. The above example would return: Cryomagnetics,CS4,2239,1.02;T <RETURN><LINEFEED> where the serial number is 2239 and the firmware version number is 1.02.

Error Handling and Command Availability: The ERROR command allows error messages to be enabled or disabled when the RS-232 interface is used. The IEEE-488.2 status mechanisms may always be used to determine if an error occurred processing a command, and the category of the error. Some commands are unavailable if the instrument menu is being accessed by an operator at the instrument, or if the instrument is in LOCAL mode. If a command available only in operate mode is received while the menus are being accessed, or if a command available only in remote mode is received while not in remote mode, a device dependent error is reported in the Extended Status Register(ESR), and the message “Command blocked” will be returned if error reporting is enabled when using the RS-232 interface.

Command Summary Table:

ERROR | Availability: Remote | Description: Set error response mode for RS-232 interface
ERROR? | Availability: Always | Description: Query error response mode
IMAG? | Availability: Always | Description: Query magnet current
IOUT? | Availability: Always | Description: Query power supply output current
LLIM | Availability: Remote | Description: Set low current sweep limit
LLIM? | Availability: Always | Description: Query current sweep limit
LOCAL | Availability: Always | Description: Return control to front panel (RS-232 Only)
MODE? | Availability: Always | Description: Query selected operating mode
PSHTR | Availability: Remote | Description: Control persistent switch heater
PSHTR? | Availability: Always | Description: Query persistent switch heater state
RANGE | Availability: Remote | Description: Set range limit for sweep rate boundary
RANGE? | Availability: Always | Description: Query range limit for sweep rate boundary
RATE | Availability: Remote | Description: Set sweep rate for selected sweep range
RATE? | Availability: Always | Description: Query sweep rate for selected sweep range
REMOTE | Availability: Operate | Description: Select remote operation (RS-232 Only)
RWLOCK | Availability: Operate | Description: Select remote operation with front panel lock (RS-232 Only)
SHIM | Availability: Remote | Description: Select shim to be queried or changed (shim option only)
SHIM? | Availability: Always | Description: Query shim selection (shim option only)
SLIM? | Availability: Always | Description: Query current limit for selected shim (shim option only)
SLIM | Availability: Remote | Description: Set current limit for selected shim (shim option only)
SWEEP | Availability: Remote | Description: Start output current sweep
SWEEP? | Availability: Always | Description: Query sweep mode
ULIM | Availability: Remote | Description: Set current sweep upper limit
ULIM? | Availability: Always | Description: Query current sweep upper limit
UNITS | Availability: Remote | Description: Select units
UNITS? | Availability: Always | Description: Query selected units
VLIM | Availability: Remote | Description: Set voltage limit
VLIM? | Availability: Always | Description: Query voltage limit
VMAG? | Availability: Always | Description: Query magnet voltage
VOUT? | Availability: Always | Description: Query output voltage
*CLS | Availability: Always | Description: Clear Status Command
*ESE | Availability: Always | Description: Standard Event Status Enable Command
*ESE? | Availability: Always | Description: Standard Event Status Enable Query
*ESR? | Availability: Always | Description: Standard Event Status Register Query
*IDN? | Availability: Always | Description: Identification Query
*OPC | Availability: Always | Description: Operation Complete Command
*OPC? | Availability: Always | Description: Operation Complete Query
*RST | Availability: Always | Description: Reset Command
*SRE | Availability: Always | Description: Service Request Enable Command
*SRE? | Availability: Always | Description: Service Request Enable Query
*STB? | Availability: Always | Description: Read Status Byte Query
*TST? | Availability: Always | Description: Self-Test Query
*WAI | Availability: Always | Description: Wait-to-Continue Command

Detailed Command Reference:

ERROR Availability: Remote Mode Command Syntax: ERROR <Error Mode> Example: ERROR 1 Parameter Range: 0 or 1 (0 - disable error reporting, 1 - enable error reporting) Description: The ERROR command enables or disables error messages when the RS-232 interface is used. Related Commands: ERROR?

ERROR? Availability: Always Command Syntax: ERROR? Response: <Error Mode> Response Example: 0 Response Range: 0 or 1 Description: The ERROR? query returns the selected error reporting mode. Related Commands: ERROR

IMAG? Availability: Always Command Syntax: IMAG? [Shim ID] Parameter Range: Z, Z2, Z3, Z4, X, Y, ZX, ZY, C2, S2, Z2X, Z2Y Response: <Magnet Current> <Units> Response Example: 87.935 A Description: The IMAG? query returns the magnet current (or magnetic field strength) in the present units. If the persistent switch heater is ON the magnet current returned will be the same as the power supply output current. If off, returns output current at the time heater was turned off. Zero if quench is detected. In SHIM mode, reports present current of the selected shim. Related Commands: UNITS, UNITS?

IOUT? Availability: Always Command Syntax: IOUT? Response: <Output Current> <Units> Response Example: 87.935 A Description: The IOUT? query returns the power supply output current (or magnetic field strength) in the present units. Related Commands: UNITS, UNITS?

LLIM Availability: Remote Mode Command Syntax: LLIM [Limit] Example: LLIM 20.125 Default Parameter: 0.0 Parameter Range: ±Maximum Magnet Current Description: The LLIM command sets the current limit used when the next SWEEP DOWN command is issued. The value must be supplied in the selected units (Amps, KG, or Tesla). Related Commands: LLIM?, ULIM, ULIM?, SWEEP, SWEEP?, UNITS, UNITS?

LLIM? Availability: Always Command Syntax: LLIM? Response: <Limit> <Units> Response Example: 20.125 A Response Range: ±Maximum Magnet Current Description: The LLIM? query returns the current limit used when the next SWEEP DOWN command is issued in the selected units. Related Commands: LLIM, ULIM, ULIM?, SWEEP, SWEEP?, UNITS, UNITS?

LOCAL Availability: Always (RS-232 Only) Command Syntax: LOCAL Description: The LOCAL command returns control the front panel keypad after remote control has been selected by REMOTE or RWLOCK. Related Commands: REMOTE, RWLOCK

MODE? Availability: Always Command Syntax: MODE? Response: <Operating Mode> Response Example: Manual Response Range: Shim or Manual Description: The MODE? command returns the present operating mode. Related Commands: MODE

PSHTR Availability: Remote Mode Command Syntax: PSHTR <State> Example: PSHTR ON Default Parameter: None Parameter Range: On or Off Description: The PSHTR command turns the persistent switch heater on or off. Related Commands: PSHTR?

PSHTR? Availability: Always Command Syntax: PSHTR? Response: 0 or 1 Description: Returns 1 if switch heater is ON, 0 if OFF. Related Commands: PSHTR

RANGE Availability: Remote Command Syntax: RANGE <Select> <Limit> Example: RANGE 0 25.0 Default Parameter: None Parameter Ranges: Range Selection: 0 or 1; Limit: 0 to Max Magnet Current Description: Sets the upper limit for a charge rate range in amps. Related Commands: RANGE?, RATE, RATE?

RANGE? Availability: Always Command Syntax: RANGE? <Select> Example: RANGE? 1 Parameter Range: 0 or 1 Response: <Limit> Response Example: 75.000 Response Range: 0 to Max Magnet Current Related Commands: RANGE, RATE, RATE?

RATE Availability: Remote Command Syntax: RATE <Range> <Sweep Rate> Example: RATE 0 0.250 Default Parameter: None Parameter Ranges: Range Selection: 0 to 3; Limit: 0 to Max Magnet Current Description: Sets the charge rate in amps/second for a selected range (0, 1, 2 = Range 1, 2, 3; 3 = Fast mode). Related Commands: RANGE, RANGE?, RATE?

RATE? Availability: Always Command Syntax: RATE? <Select> Example: RATE? 1 Parameter Range: 0 to 3 Response: <Rate> Response Example: 0.125 Response Range: 0 to Max Magnet Current Related Commands: RANGE, RANGE?, RATE

REMOTE Availability: Operate (RS-232 Only) Command Syntax: REMOTE Description: Takes control of the CS-4 via remote interface, disabling front panel except Local button. Related Commands: LOCAL, RWLOCK

RWLOCK Availability: Operate (RS-232 Only) Command Syntax: RWLOCK Description: Takes remote control with front panel locked out. Related Commands: LOCAL, RWLOCK

SHIM Availability: Remote Mode (Shim mode only) Command Syntax: SHIM [Enable or Disable] <Selection> Examples: SHIM Z4, SHIM Enable Z3, SHIM Disable Z3, SHIM Enable All, SHIM Disable All Default Parameter: None Parameter Range: Z, Z2, Z3, Z4, X, Y, ZX, ZY, C2, S2, Z2X, Z2Y Description: Selects a shim to be controlled or queried, or enables/disables shims. Related Commands: IMAG?, SHIM?, SLIM, SLIM?

SHIM? Availability: Always (Shim mode only) Command Syntax: SHIM? [Query selection] Response: <Shim selection> <Enabled or Disabled> Response Example: ZX Enabled Response Range: Z, Z2, Z3, Z4, X, Y, ZX, ZY, C2, S2, Z2X, Z2Y Related Commands: IMAG?, SHIM, SLIM, SLIM?

SLIM Availability: Remote Mode (Shim mode only) Command Syntax: SLIM <Limit> Example: SLIM -5.837 Default Parameter: 0.0 Parameter Range: ±30.000 Description: Sets the current limit for the selected shim. Related Commands: IMAG?, SHIM?, SLIM?, SWEEP

SLIM? Availability: Always (Shim mode only) Command Syntax: SLIM? Response: <Limit> A Response Example: 5.923 A Response Range: ±30A Related Commands: IMAG?, SHIM, SLIM, SWEEP

SWEEP Availability: Remote Mode Command Syntax: SWEEP <Sweep Mode> [fast or slow] Examples: SWEEP UP, SWEEP UP FAST Default Parameter: None Parameter Range (Manual): UP, DOWN, PAUSE, or ZERO Parameter Range (Shim): LIMIT, PAUSE, or ZERO Description: Causes supply to sweep output current to specified limit at programmed rate. Related Commands: LLIM, LLIM?, SLIM, SLIM?, SWEEP?, ULIM, ULIM?, UNITS, UNITS?

SWEEP? Availability: Always Command Syntax: SWEEP? Response: <Mode> [fast] Response Example: sweep up fast Response Range: sweep up, sweep down, sweep paused, or zeroing Related Commands: LLIM, LLIM?, SLIM, SLIM?, SWEEP, ULIM, ULIM?, UNITS, UNITS?

ULIM Availability: Remote Mode Command Syntax: ULIM [Limit] Example: ULIM 65.327 Default Parameter: 0.0 Parameter Range: ±Maximum Magnet Current Description: Sets current limit used when next SWEEP UP is issued. Related Commands: LLIM, LLIM?, SWEEP, SWEEP?, ULIM?, UNITS, UNITS?

ULIM? Availability: Always Command Syntax: ULIM? Response: <Limit> <Units> Response Example: 65.327 A Response Range: ±Maximum Magnet Current Related Commands: LLIM, LLIM?, SWEEP, SWEEP?, ULIM, UNITS, UNITS?

UNITS Availability: Remote Mode Command Syntax: UNITS <Unit Selection> Example: UNITS T Parameter Range: A, T, G, or kG Description: Sets display and input units (Amps, Tesla, or kilogauss). Related Commands: IMAG?, IOUT?, LLIM, LLIM?, ULIM, ULIM?, UNITS?

UNITS? Availability: Always Command Syntax: UNITS? Response: <Selected Units> Response Example: T Response Range: A, T, or kG Related Commands: IMAG?, IOUT?, LLIM, LLIM?, ULIM, ULIM?, UNITS

VLIM Availability: Remote Mode Command Syntax: VLIM <Voltage Limit> Example: VLIM 5.0 Parameter Range: 0.0 to 10.0 Description: Sets power supply output voltage limit. Related Commands: VLIM?, VMAG?, VOUT?

VLIM? Availability: Always Command Syntax: VLIM? Response: <Voltage Limit> Response Example: 4.75 V Response Range: 0 to 10.00 Related Commands: VLIM, VMAG?, VOUT?

VMAG? Availability: Always Command Syntax: VMAG? Response: <Magnet Voltage> Response Example: 4.75 V Response Range: -10.00 to +10.00 Related Commands: VLIM, VLIM?, VOUT?

VOUT? Availability: Always Command Syntax: VOUT? Response: <Output Voltage> Response Example: 4.75 V Response Range: -12.80 to +12.80 Related Commands: VLIM, VLIM?, VMAG?

*CLS Availability: Always Command Syntax: *CLS Description: Clears Standard Event Status Register (ESR) and resets MAV bit in Status Byte Register (STB). Related Commands: None

*ESE Availability: Always Command Syntax: *ESE <mask> Example: *ESE 255 Default Parameter: 0 Parameter Range: 0 to 255 Description: Sets mask into Standard Event Status Enable Register (ESE). Related Commands: *ESE?

*ESE? Availability: Always Command Syntax: *ESE? Response: <ESE Mask> Response Example: 255 Response Range: 0 to 255 Related Commands: *ESE

*ESR? Availability: Always Command Syntax: *ESR? Response: <Standard Event Status Register> Response Example: 128 Response Range: 0 to 255 Description: Returns contents of Standard Event Status Register and clears it. Status Byte Bit Allocations: Bit 0: Operation Complete Bit 1: Request Control Bit 2: Query Error Bit 3: Device Dependent Error Bit 4: Execution Error Bit 5: Command Error Bit 6: User Request Bit 7: Power On Related Commands: *ESE, *ESE?

*IDN? Availability: Always Command Syntax: *IDN? Response: <Manufacturer>,<Model>,<Serial #>,<Firmware Level> Response Example: Cryomagnetics,CS4,2239,1.02 Serial # Range: 2000 to 9999 Firmware Level Range: 1.00 to 9.99 Related Commands: None

*OPC Availability: Always Command Syntax: *OPC Description: Places Operation Complete message in Standard Event Status Register (ESR). Related Commands: *OPC?

*OPC? Availability: Always Command Syntax: *OPC? Description: Places ASCII ‘1’ in output queue. Related Commands: *OPC

*RST Availability: Always Command Syntax: *RST Description: Reset command per IEEE Std 488.2-1992 (does not change power supply operation due to safety). Related Commands: None

*SRE Availability: Always Command Syntax: *SRE <mask> Example: *SRE 255 Default Parameter: 0 Parameter Range: 0 to 255 Description: Sets mask in Service Request Enable Register (SRE). Related Commands: *SRE?

*SRE? Availability: Always Command Syntax: *SRE? Response: <SRE Mask> Response Example: 255 Response Range: 0 to 255 Related Commands: *SRE

*STB? Availability: Always Command Syntax: *STB? Response: <Status Byte> Response Example: 65 Response Range: 0 to 255 Status Byte Bit Allocations: Bit 0: Unused Bit 1: Unused Bit 2: Quench condition present Bit 3: Power loss condition present Bit 4: MAV (Message Available) Bit 5: ESB (Extended Status Byte) Bit 6: MSS (Master Summary Status) Bit 7: Remote lockout (menu or local selected)

*TST? Availability: Always Command Syntax: *TST? Response: <Self test status> Response Example: 1 Response Range: 1 Related Commands: None

*WAI Availability: Always Command Syntax: *WAI Description: Wait-to-Continue command (sequential execution, no-operation-pending flag is always TRUE). Related Commands: OPC, *OP

Appendix C - Calibration Procedures

Appendix C Calibration Procedures

C.1. Calibration Menu The Calibration menu provides access to submenus used to calibrate the power supply functions: Analog Inputs, Analog Outputs, Power Output, Power PID.

C.2. Analog Input Calibration Menu Calibrates ±Iset, ±Vset, and ±Mag.Vin. inputs (-10V to +10V for Iset and Mag.Vin; 0V to +5V for Vset).

C.2.1. Set Current Calibration (±Iset) C.2.1.1. Current Limit Offset: Set Current Limit source to Analog Input. Apply 0.000 V to ±Iset inputs, observe Current Limit on display. In Calibration menu under Set Current <Offset>, compute: New Offset = Present Offset – Displayed Current Limit Enter New Offset and verify displayed Current Limit is 0.000A.

C.2.1.2. Current Limit Gain: Apply 5.000 V to ±Iset inputs (should read 50.000A). In Set Current <Gain>: New Gain = (Present Gain) x (50.000) / (Displayed Current Limit) Verify displayed Current Limit is 50.000A at +5V and -50.000A at -5V. Return source to Programmed.

C.2.2. Set Voltage Calibration (±Vset) C.2.2.1. Voltage Limit (Charge Rate) Offset: Set Voltage Limit source to Analog Input. Apply 0.050 V to ±Vset, observe display. In Set Voltage <Offset>: New Offset = Present Offset – Displayed Voltage Limit Enter New Offset and verify displayed Voltage Limit is 0.05V.

C.2.2.2. Voltage Limit (Charge Rate) Gain: Apply 4.500 V to ±Vset (should read 4.50V). In Set Voltage <Gain>: New Gain = (Present Gain) x (4.50) / (Displayed Voltage Limit) Enter New Gain and verify display is 4.50V. Return source to Programmed.

C.2.3. Magnet Voltage Calibration (±Mag.Vin.) C.2.3.1. Magnet Voltage Offset: Apply 0.00 V to ±Mag.Vin. inputs. In Magnet Voltage <Offset>: New Offset = – (Present Offset + Displayed Magnet Voltage Offset) Enter New Offset and verify display reads 0.00V.

C.2.3.2. Magnet Voltage Gain: Apply 4.50 V to ±Mag.Vin. inputs (should read 4.50V). In Magnet Voltage <Gain>: New Gain = (Present Gain) x (4.50) / (Displayed Magnet Voltage) Enter New Gain, verify display reads 4.50V at +4.50V and -4.50V at -4.50V.

C.3. Analog Output Calibration Menu Calibrates ±Iout, ±Vout, and ±Mag.Vout analog outputs (configured for 0 to 10V operation).

C.3.1. Analog Output Current and Voltage Calibrations (±Iout & ±Vout): Connect load. At zero amps and zero volts, adjust Output Current Offset and Output Voltage Offset until 5.0 V is measured at ±Iout and ±Vout with a DVM. Set current limit to >=10A, ramp up, measure Iout: New Gain = (Present Gain) x (Displayed Current) / ((Measured Iout - 5.0) x 20) Measure Vout: New Gain = (Present Gain) x (Displayed Voltage) / (Measured Vout - 5.0) Enter values in respective Gain fields.

C.3.2. Analog Output Magnet Voltage Calibration (±Mag.Vout): Apply 0.00 V to Mag.Vin, adjust Magnet Voltage Offset until ±Mag.Vout is 5.0 V. Apply 4.50 V to Mag.Vin: New Gain = (Present Gain) x (4.50) / ((Measured Mag.Vout. - 5.00) x 2) Enter in Magnet Voltage Gain field.

C.4. Power Output Calibration Menu Calibrates power supply output current. Figure C.4 values: Output Gain (1.0212), Output Offset (0.0500), DAC Offset (0.0000), Swamp Resistor (20.00).

C.4.1. Power Output Gain and Offset: Measure output at 0.500 A: New Offset = 0.500 - (Measured Current) - (Present Offset) Enter in Output Offset field. Set limit to 50-80% max, sweep up, PAUSE, wait 15-20 min: New Gain = (Present Gain) x (Displayed Current) / (Measured Current) Enter in Output Gain field.

C.4.2. DAC Offset: Sweep rate at 0.001 A/Sec, upper limit 0.5 A. Start sweep, observe initial values, return to STANDBY: New Offset = (Present Offset) - (Measured Current) Enter in DAC Offset field. Repeat until sweep starts within 5 mA of zero (30s delay between iterations).

C.4.3. Swamp Resistor: Internal 6-ohm resistor aids stability with inductive loads. Leakage current is calculated and subtracted from displayed current. Changing external parallel resistors requires updating this setting.

C.5. Power PID Calibration Adjusts PID parameters (sampling interval 200 ms). Proportional gain (~0.5), Integral gain (~1.0), Differential gain (max ~1.300). Restore Factory Defaults option available.

Appendix D - Shim Supply Option

Appendix D Shim Supply Option

D.1. Overview The Shim Supply Option provides hardware and software to control up to 12 independent superconducting shim coils (e.g., Z, Z2, Z3, Z4, X, Y, ZX, ZY, C2, S2, Z2X, Z2Y) in addition to the main magnet.

D.2. Shim Option Description Features: a) 12 persistent switch heater output channels. b) Polarity selection to allow shim multiplexing. c) 0 – 100mA heater current range. d) +/- 30 amp output current range. e) Automatic shim dumping during main coil energizing/discharging. f) Independent and global shim heater enable/disable.

In standard mode, each channel drives one switch heater with common return. In multiplexed mode, positive and negative currents select different switch heaters sharing wire pairs via diodes.

D.3. Setup D.3.1. MANUAL Mode: During main magnet ramping, mutual inductance induces current in shim coils. The CS-4 periodically pulses each enabled shim heater for ~6 seconds to dump induced current. This can be globally inhibited if needed.

D.3.2. SHIM Mode: Pressing [Mode] toggles between MANUAL and SHIM mode when the supply is in STANDBY and all shims are dumped/disabled. In SHIM mode, left/right arrows cycle through enabled shims.

D.3.3. Selection Menu: [MENU] displays the status and current of all shim coils. [SHIFT-MENU] allows globally disabling or enabling all shims.

D.3.4. Setup Menu: Allows editing Target Current, Present Current, Enable/Disable, Output Channel (1-12, + or -), and Persistent Switch Heater Current (0-100 mA).

D.3.5. Hardware Connections: DB-15 connector on rear panel connects to shim heaters: Pin 1: Channel 1 Pin 2: Channel 2 Pin 3: Channel 3 Pin 4: Channel 4 Pin 5: Channel 5 Pin 6: Channel 6 Pin 7: Common Pin 8: Common Pin 9: Channel 7 Pin 10: Channel 8 Pin 11: Channel 9 Pin 12: Channel 10 Pin 13: Channel 11 Pin 14: Channel 12 Pin 15: Common

D.4. Operation D.4.1. Energizing Shims (Initial Setting): a) Select shim. b) Turn ON persistent switch heater ([PSHtr] + [Enter]). c) Wait ~10 seconds to warm. d) Press [↑] or [↓] to sweep to current limit. e) Turn OFF switch heater ([PSHtr] + [Enter]). f) Wait ~10 seconds to cool. g) Press [Zero] to discharge leads to zero.

Resetting Shim Currents (Second Pass): Bring leads to target current, turn heater ON, wait 10s, turn heater OFF, wait 10s, then either zero leads or switch directly to next shim.

D.4.2. Discharging Shims: Sweep leads to current limit, turn heater ON, wait 10s, sweep to zero with [Zero], turn heater OFF, wait 10s.

CAUTION: When changing back to MANUAL mode, the ±30A firmware safety limit is removed and the supply can source its full current (e.g. 100A). Ensure power leads are swapped back to main magnet terminals.