LANL Fusion Capabilities

Summary

This presentation outlines Los Alamos National Laboratory’s (LANL) fusion research capabilities, priorities, and experimental facilities presented at the INFUSE workshop in January 2019. It highlights LANL’s contributions to magnetic and inertial fusion energy sciences (FES), including field-reversed configuration (FRC) research, the Plasma Liner Experiment (PLX), diagnostic development for facilities like W7-X and DIII-D, and advanced theoretical and computational modeling of plasma exhaust, runaway electrons, and disruptions.

Title Slide - LANL Fusion Capabilities

LANL Fusion Capabilities INFUSE workshop Jan 22-23, 2019 Los Alamos National Laboratory (EST. 1943) Managed by Triad National Security, LLC for the U.S. Department of Energy’s NNSA

Los Alamos has a long history of fusion research

• Today magnetic and inertial fusion work resides in the Physics Division, Theory Division, and X Division (Weapons). There are also related capabilities in detectors, radiation damage, and tritium handling. • Dr. John Kline ([email protected]) is the present Fusion Energy Sciences (and Inertial Fusion) program manager, and a point-of-contact.

Historical references shown:

James Tuck, Perhapsatron, 1953
Ivy Mike, 1952

LANL FES Priorities for FY20 & FY21

• Core Program Priorities

Burning Plasma Science: Foundations • Theoretical and computational work on the fundamental description of magnetically confined plasmas and the development of advanced simulation codes, including validation experiments. • Enabling R&D needed to support the continued improvement of the experimental program in the area of diagnostics.
Burning Plasma Science: Long Pulse • The LANL collaboration on W7-X in Germany provides an opportunity to develop and assess 3D divertor configurations for long-pulse, high-performance stellarators. • Materials & Fusion Nuclear Science supports the development, characterization, and modeling of structural and plasma-facing materials used in the fusion environment. • Program Priorities for Term Grants
Discovery Plasma Science • Supports research that explores the fundamental properties and complex behavior of matter in the plasma state to improve the understanding required to control and manipulate plasmas for a broad range of applications.

FRC’s were developed in Russia and Los Alamos

Field Reversed Theta Pinches at Los Alamos FRC’s are high beta plasmas, with many interesting features.

Key areas shown:

Schematic of the FRX-C field-reversed theta pinch (Cables from capacitor banks, FRX-C feedplate, FRX-C plasma formation coil, Vacuum tube).
Phases of FRC formation in a field-reversed theta pinch (Preionization (0), Field Reversal (1), Radial Compression & Field Line Connection (2), Axial Contraction (3), Equilibrium (4), Separatrix).
LANL FRX-C/T theta pinch (left) and dc magnet coils surrounding the translation chamber (right).
MHD simulation of poloidal flux for FRC translation.
Experimental measurements of excluded magnetic flux for FRC translation.

Today FRC plasmas are still being explored

Fast forward to 21st Century: Resurgence of FRCs through private investments

Tri-Alpha Energy, Inc (Foothill Ranch, CA): Divertor, South θ-Pinch, Form FRC, Translate, Colliding CTs, Confinement, North θ-Pinch, Divertor.
Helion Energy (Redmond, WA): Plasma gun, Compression chamber, Accelerator coils, Plasma gun.
General Fusion (Burnaby, BC): Plasma Injector, Rotor, Liquid metal, Core implosion, Heat Exchanger, Steam Turbine generator, Core Injection Pump.

Magnetized Plasma Team in P-24 Plasma Physics

Team Leader: Glen Wurden ([email protected]) Staff: Hsu, Weber, Langendorf, Dunn, Shimada Postdocs: Tom Byvank, Kevin Yates, John Boguski Student: Chris Roper (Summer)

We do experimental plasma work for FES, ARPA-E, and NNSA sponsors, with national and international partners, including small businesses. We use our knowledge of plasma diagnostics, pulsed power expertise, and HED plasmas in the areas of fusion energy, weapons support, and basic plasma science.

The Plasma Liner Experiment at LANL

• This was an ARPA-E “ALPHA” project. • Presently PLX has 18 plasma guns in a hemispherical geometry, on a 2.75 m diameter chamber. • It is being used to study the merging hypersonic plasma jets. • Later in 2020, it may be upgraded to a full set of 36 guns. • PI: Sam Langendorf, [email protected]

LANL leads an ARPA-E “capabilities” team

LANL and the University of Nevada, Reno will be providing three soft x-ray diagnostics to one or more ARPA-E transformative fusion facilities, starting with FuZE and ZAP at the University of Washington in 2020. They will provide information on electron temperature, hot spots, and impurity radiation.

Diagnostics layout includes:

Ross-filtered SXR detectors (Pinhole/filters, Phosphor/PMT)
Fast-gated Framing Camera (Pinhole/filter, Phosphor)
EUV Spectrometer (Slit/filter)
Monitoring Hot Plasma via Soft X-rays

High resolution imaging on the W7-X stellarator

Infrared, visible, and ultraviolet

One of W7-X’s 10 divertors
Reentrant endoscope using metal mirrors, shutter, pinhole, and sapphire vacuum window
FLIR Infrared camera, 512 x 512 pixels @310 Hz, or 64x16 pixels @ 3kHz.
PCO Edge 5.5 visible camera, 1 Megapixel useful image, 60 Hz frame rate at 10 msec exposure. 5 narrow-band filters.
Ocean Optics QE65000 UV spectrometer, 225-345 nm, 20 msec per spectrum, sees 20 or so lines, including He II, B IV, O V, C II, as well as low charge states of test impurities, such as Fe, Mo, N, Ne.

We collaborate at national and international facilities

Photograph and caption: W7-X “One Team” in the control room, Oct. 2018.

LANL Advanced Diagnostics

What: A new type of diagnostic using laser inverse Compton scattering to measure soft x-rays generated from laser photons scattering off of runaway (relativistic) electrons in the DIII-D tokamak.

Where we are: ( $480 k F Y 18) M u l t i - in s t i t u t i o n d es i g n s t u d y f or L a ser I n v er se C o m pt o n S c a tt er in g (L I C S) D ia g n os t i c f or R u na w a y E l ec t r o nm e a s u r e m e n t so n t h eD I I I - D t o k amak i s in p r o g r ess . C o m pl e t i o n o f r e v i e w s b y e a r l y F Y 20. P r ese n t in v es t m e n t i s$ 820k for design study (LANL/GA/UCSD/Woodruff), and $1.15M for SBIR Phase I and Phase II laser development effort (Voss Scientific).

Where we are going: In FY21, The LICS runaway electron diagnostic design for DIII-D will be ready to move to a construction and installation phase, contingent on DIII-D schedule, port negotiations, and funding.

Images:

LANL 4 strip gated x-ray imager
Inside view of 105 tangential port on DIII-D
Voss Scientific prototype laser

We test our detectors at world class x-ray and neutron sources

• Argonne Advanced Photon Source (x-rays) • Omega and NIF (x-rays, neutrons) • P-24 soft x-ray sources • Physikalisch-Technische Bundesanstalt (PTB) accelerator in Braunschweig, Germany (neutrons) • Sandia Ion Beam Facility (neutrons)

LANL Focus (i): Solution to Plasma Particle & Power Exhaust in Reactors

Where we are: • Identification of the plasma power exhaust challenge aggravated by light ion reflection by high-Z metal divertor/wall surface

MD quantification of He reflection from W surface
Apply recent advances in sheath theory to tie ion power recycling to target plasma temperature. • Fundamental advances in quantification of sheath energy transmission coefficients
Bohm speed (from Bohm criterion) is set by electron heat flux to the wall: u_Bohm ≡ sqrt((3 k_B (T_i^SE + Z β T_e^SE)) / m_i - Z β (m_e / m_i) (j^2 / (e n_e^SE)^2))
Full kinetic simulations quantify sheath energy transmission
A fully kinetic sheath model for the collisionless sheath of a collisional plasma → tokamak regime • Parallel transport along open field lines with magnetic trapping and varying collisionality

Where we are going: • Incorporate all relevant atomic processes to understand:

Radiation cooling near & detachment at divertor
Impurity upstream transport and radiative cooling in the scrape-off layer
Radiation cooling near & inside the magnetic separatrix, and impurity screening

How we are going to do it: • Two complementary approaches:

Incorporating discrete atomic processes in VPIC kinetic code (a prototype is in place - FY20-21)
Coupling plasma multi-fluid solver to collisional-radiative model (a light-weight CR module is in place – FY20; collaborating with SNL on multi-fluid solver (FY20-21) ← SciDAC & ASCR)

LANL Focus (ii): Understanding Runaway Generation, Transport, & Dissipation

Where we are: • Physics picture of runaway vortex defines what runaways means in a tokamak

Runaway electrons are really run-around electrons in momentum space: cyclic acceleration and deceleration in the presence radiation damping and pitch angle scattering
Topological transition to runaway vortex → avalanche threshold; geometry of runaway vortex → avalanche growth rate • The essential role of partial screening in mitigated disruption by high-Z impurities
Increased runaway amplification potential via avalanche process → make the matter worse
Increased runaway spatial transport + Ware pinch → impact the spatial distribution of runaway avalanche • Toroidicity has surprising effect on runaways in the large E field regime, as required by current ITER DMS design

Where we are going: • Incorporate more accurate description of the atomic processes in the presence of a runaway component

QED corrections in the relativistic limit can significantly modify the cross sections: large angle collision and excitation due to free-bound electron collisions. • Account for the full toroidal geometry plus 3D magnetic fields • All known runaway seeding mechanisms

How we are going to do it: • Sophisticated collisional-radiative model accounts for relativistic electron component (a working prototype is producing intriguing results – FY20) • Bringing various cross sections directly into relativistic Fokker-Planck solver FY20-21 • Full geometry and 3D fields in both continuum (FY-21) and particle (FY20) solvers

LANL Focus (ii): Integrated Modeling of Disruption Dynamics

Where we are: • MHD and extended MHD (PIXIE3D) modeling of the onset of tokamak disruption through major MHD instabilities

Reconnection & post-thermal quench current spike • Multi-fluid (Drekar, TDS-SNL) modeling of neutral gas and plasma interaction
Gas and injected pellet assimilation • Boundary plasma kinetic modeling by VPIC
Understand the PMI in disrupting plasma (with halo current) and set boundary condition for integrated modeling using quasi-neutral plasma models • Gyro-fluid (BOUT++, TDS-LLNL) modeling of edge transport and turbulence and resulting disruption-induced transient particle and power load on PFC. • Gyrokinetic (GTS, TDS-PPPL) modeling of thermal quench in the presence of 3D fields and hot tail formation (or not) • Self-consistent E & B field evolution with runaway electrons in an axisymmetric tokamak undergoing rapid radiative cooling

Where we are going: • First step: integrate runaway electron dynamics into self-consistent electric field evolution to follow the macro-dynamics of a disrupting plasma. • Second step: integrate plasma macro-dynamics that accounts for the runaway electrons with transport models that describes the seeding mechanisms as well as the thermal bulk.

How we are going to do it: • First step: a self-consistent electromagnetic field solver + runaway drift kinetic solver in a full torus, initially assuming toroidal symmetry (FY20), later including 3D fields (FY21)

Include partial-screening, Dreicer flux, avalanche, Ware pinch • Second step: TBD depending on what we learn.

Note: McDevitt is taking the lead to acquire an ITER contract on DMS.

Fusion Nuclear Science Highlights and Plans

• The HPL is a pilot scale gas handling and metal hydride storage bed system that can be used for experimental, design and validation studies for tritium processing. The benefit of the HPL is that by using hydrogen instead of tritium the safety design and overhead cost associated radioactive processing can be reduced by using the hydrogen isotope as a surrogate for tritium. • The Tritium System Test Assembly (TSTA) database has completed the initial upload of documentation. FES and LANL are currently assessing export control requirements to determine the best process to open the database to open access. • The Liquid Metal / Plasma Facing Components (LM/PFC) Working Group has been tasked with studying the impact of this type of a first wall concept to FNSF. LANL is assisting with a design assessment for a tritium plant to support this design.

Current / Future Research Details (FY18/19): • Completed upgrades to HPL data acquisition and control system. Control and data collection has been validated. Testing of PMR for comparison with previous reported data for ITER TEP design is planned for later this year • Export control issue resolution to allow for transfer TSTA Database to open server for tritium community • Participate in FESS for tritium plant modeling and support of B/TP program

Recent Reports / Presentations: • W. Kirk Hollis, et al., LM PFC Meeting, LM PFC Working Group Meeting. FES Germantown, August 2018 • Hollis, W. Kirk, et at. Plant-wide tritium flow and control, definitions and modeling

New Start: Coupled plasma - irradiation PMI capability at LANL (Y. Wang)

The facility allows to examine dynamics of displacement damage and/or He effects on D transport (trapping, diffusion, and release) when defects and He are concurrently produced in PFM under various target temperatures.

Ion Beam Materials Laboratory facilities shown:

Alphatross & SNICS-II ion sources
NEC 3 MV Tandem Ion Accelerator
Varian Production Ion Implanter (Varian 200 kV)
Five beamlines
Tandem Operation Terminal
Dual-beam chamber
Danfysik 200 kV Research Implanter
EH400 Plasma Source: Energy: 40 – 300 eV He, Flux: 1.5x10^21 ions/m^2/s

LANL FES Vision for Existing & Future Programs

Los Alamos contributes to the National Fusion Energy Sciences Program 10-year strategy, building upon and exercising unique LANL capabilities in magnetic fusion energy and discovery science theory, modeling, simulation, experiments, and technologies. As a DOE multipurpose National Lab, we are in the vanguard of deploying new and novel methodologies, instrumentation, and analyses aligned with the FES Ten-Year Perspective, including tokamak transient control, collaborations on the world-leading stellarator, plasma-material interactions, tritium science, and basic plasma physics discovery.