Pre-ionization experiments on a high-density field reversed configuration suitable for magnetized target fusion

Summary form only given. We present the progress on the high-density Field Reversed Configuration (FRC) experiment presently being studied at LANL. This FRC will be the target plasma for Magnetized Target Fusion (MTF) experiments; heating it by compressing it inside an imploding flux conserver should allow access to fusion conditions. Diagnosing the FRC plasma will be challenging due to the short timescales, high energy densities, high magnetic fields, and restricted access. Our goal is an FRC with n/spl sim/10/sup 17/ cm/sup -3/, T/sub 1/=T/sub e/=/spl sim/100-300 eV, B/spl sim/5 T, and a lifetime of 10-20 /spl mu/s. Results to date on the Pre-Ionization (PI) phase of the experiment will be presented. From our previous experience, the PI process is crucial for good FRC formation, and not well understood. Initial attempts will include using the ringing theta coil discharge (/spl theta/-PI) technique, which ionizes the gas by impressing a rapidly oscillating (/spl sim/300 kHz) axial magnetic field superimposed upon the slower-timescale magnetic bias field, of comparable magnitude. The PI process occurs just prior to applying a much (10/spl times/) higher reverse field that causes the frozen-in field lines to radially contract and form the closed field lines for the FRC.