Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
The STX experiment was operated during the construction phase of TCS, primarily to investigate the ability of the Rotating Magnetic Field (RMF) to directly form an FRC, without the usual theta pinch technology. STX utilized a 25G RMF at 350kHz to form 2m long by 0.2m radius FRCs. Plasmas were typically fully ionized deuterium with a temperature of 60 eV and a peak density of 5x10^18m^-3. Axial confining fields of 100G maintained a true vacuum boundary around the plasma and allowed for the study of FRC RMF equilibrium interactions. Key findings are that the RMF drove strong radial and axial flows, produced radial profiles markedly different from those of theta pinch formed FRCs, and resulted in enhanced particle and energy confinement. Although the FRCs were usually not sustained, they evolved into an interesting mirror like configuration that also exhibited enhanced particle and energy confinement. Issues discussed include the importance of the RMF driving an azimuthal current distribution consistent with that of the FRC, possible benefits of varying the average beta condition, and potential RMF antenna length limits set by the tendency of driven axial flows to screen the RMF from the plasma.