|icc_modular_bank.pdf||2006-02-21 12:41:11||Bick Hooper|
A Modular Capacitor Bank for SSPX
Author: Bick Hooper
Submitted: 2005-12-22 12:08:06
Co-authors: H. S. McLean, R. D. Wood, B. I. Cohen, D. N. Hill
PO Box 808
Livermore, CA 94550
A new, modular capacitor bank being constructed for SSPX will provide unprecedented flexibility in controlling helicity injection and sustainment. The bank consists of 30 modules (C= 4.4 mFd, V=5kV, 1.65 MJ) which can be fired with or without the original banks (2 MJ). The inductor in each module has taps providing 4 values from 0µH to 30µH (+ ~ 1.7 µH leads). Each module can be fired independently, providing significant pulse-shaping capability. Operation of the first 15 modules with a plasma is scheduled for February, 2006. The capacitor bank design has been incorporated into the NIMROD MHD simulations and several experiments modeled. A high current (I_gun > 800 kA peak) is predicted to yield magnetic fields > 0.9T at the flux conserver. Good magnetic flux surfaces form during the > 5 ms ramp-down phase of the discharge yielding good energy confinement. Examination of the steady-state which would be achievable if the current pulse could be extended yield magnetic fields at the flux conserver > 1.1T and poloidal flux amplification = 6.7. Simulations have also been used to predict the results of pulsed refluxing experiments in which a current pulse is added to a steady current, raising λ_gun=µ_0*I_gun/Ψ_gun (Ψ_gun = bias poloidal flux) sufficiently to add net poloidal flux to the spheromak. Previous experiments and simulations in SSPX have suggested that this provides a possible route to a quasi-steady state spheromak with possible reactor applications. The pulse-length and amplitude of these new simulations, which can be applied to the experiment using the new bank, are varied to predict the most promising experimental route to test the concept.