6.5 T.Matsumoto CT2016

Compact Toroid Injection into C-2U FRC US-Japan CT2016, August 24 Tadafumi Matsumoto Nihon University NIHON UNIVERSITY CT-Work Shop2016 2 Presenter: Tadafumi Matsumoto Collaborations Nihon University University of California at Irvine Tri Alpha Energy • This project has been conducted in part under the MOU on the research cooperation between UCI and NU. • Integral partnership • Development of a compact toroid injector for particle refueling CT-Work Shop2016 3 Presenter: Tadafumi Matsumoto H. Gota T. Roche T. Asai* E. Garate E. Granstedt I. Allfrey T. Valentine J. Kinley, C. Hooper M. Cordero P. Feng W. Waggoner M. Conroy M. Morehouse D. Sheftman T. Tajima* *Nihon University Acknowledgements *UCI CT-Work Shop2016 4 Presenter: Tadafumi Matsumoto • Motivation • CT Injector Overview • CT injection into C-2U FRC • Upgrade • Summary Outline CT-Work Shop2016 5 Presenter: Tadafumi Matsumoto Outline • Motivation • CT Injector Overview • CT injection into C-2U FRC • Upgrade • Summary CT-Work Shop2016 6 Presenter: Tadafumi Matsumoto Requirement for CT Injection • In C-2U particle loss rate was 2.0 – 4.0× 10 18 / ms • To penetrate the FRC, the kinetic energy density of the CT must be higher than 4 k J/m 3 , which is magnetic field energy inside the confinement vessel, e.g., density of CT 1×10 15 cm -3 , velocity 70 km/s • The CT Injector is a viable refueling candidate Motivation 012345 0.5 1.0 1.5 2.0 2.5 0 time (ms) Particle number (x10 19 ) Loss rate: 2.5x10 18 Time evolution of particle loss rate of the C-2U FRC CT-Work Shop2016 7 Presenter: Tadafumi Matsumoto Outline • Motivation • CT Injector Overview Ø Developed CT injector Ø Test Stand Ø CT Parameters • CT injection into C-2U FRC • Upgrade • Summary CT-Work Shop2016 8 Presenter: Tadafumi Matsumoto Tungsten coating • The surface of the inner electrode is coated with tungsten by Vacuum Plasma Spraying Extension electrode • The roles of the extension electrode are; protect ceramic break from the plasma, and suppress diffusion of the magnetic field. Gas port Magnetized Coaxial Plasma Gun Outer Electrode (I.D 83.1 mm) Bias Coil Inner Electrode (O.D. 54 mm) Extension Gas Puff Valve (1) Biasing magne7c field applied and working gas is injected between electrode. (2) Forma7on bank is triggered to begin breakdown. The plasma is accelerated by Lorentz force. (3) The accelerated plasma is captured by bias field. Then the reconnec7on occurs. (4) The magne7zed plasma is ejected. Working gas Bias field Breakdown Accelerate by J r ×B θ capture Reconnec7on Toroidal current CT-Work Shop2016 9 Presenter: Tadafumi Matsumoto CT Injector Dri M tube • Magne7c probe • Dispersion Inter. • PMT • Triple Langmuir probe Transverse Field Coil Expansion glass chamber • Magne7c probe • PMT • Triple Langmuir probe å Drift tube • The drift tube diagnostics measure typical CT parameters; velocity, density, and temperature. Glass chamber • The transverse magnetic field coil simulates C-2U’s magnetic field. Test Bed with Transverse magnetic field coil CT-Work Shop2016 10 Presenter: Tadafumi Matsumoto Transverse field region èCT Compressed Field-free region èCT Expands CT was compressed by magnetic field w/o Transverse field w/ Transverse field CT-Work Shop2016 11 Presenter: Tadafumi Matsumoto n Required parameters >70 km/s, 1.0×10 15 cm -3 n Gun current up to 190 k A n Total energy of CT up to 0.7 k J n Velocity >100 km/s n Density 1.5 - 3.5×10 15 cm -3 n Electron temperature 20 - 40 e V n Energy Density 50 k J/m 3 CT Performance n Developed CT injector achieved the requirement n CT will penetrate C-2U Field n Diameter of CT in the transverse field is 5-10 cm according to probe measurements CT Injec_on across transverse field