Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
A large tube based power supply was built by LANL to power a Rotating Magnetic Field (RMF) for the TCS FRC sustainment experiment at the U. of Washington. Two antenna sets, of about 1.8 \muH each are each connected in parallel with capacitors to form parallel tuned circuits. The antennas can be run at up to ±10kV, yielding up to ±11kA at a frequency of 80kHz. Two antennas, phased 90 deg apart, produce an RMF with a field strength up to 70G over a volume 1.5m long and 1m in diameter. The power supply consists of two legs with (6) 250A, 30kV triodes each, and is capable of supplying over 5MW of power for several msec. The power absorbed by the FRC is reflected by the phase differences between the antenna voltages and currents. Since the FRC is maintained in quasi steady-state, energy confinement times can be determined. A simple 1-D model, assuming radiative (measured with a silicon bolometer), charge exchange, and convective losses has been used to estimate particle and energy confinement times, and hence ionization rates and neutral particle fractions or effective recycling rates. Collisions with neutrals are one mechanism proposed to prevent ion spin-up by electron friction. The neutral particle fractions necessary for power balance are compared with those calculated to be necessary to account for low measured values of ion spin-up.