Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
We compare the results from the Sustained Spheromak Physics eXperiment, SSPX, with NIMROD simulations in order to better understand formation and to improve efficiency in the experiment. SSPX routinely forms spheromaks with n=1 present during formation, and n=2 during decay. NIMROD simulations, with SSPX-similar geometry, reproduce this mode-behavior and suggest that the field strength of the spheromak will grow until the n=1 mode reaches saturation. Such a saturated state is not anticipated by simple helicity considerations which, instead, point to the continued rise in field-strength of the spheromak, limited ultimately by dissipation. We explore the mechanisms that lead to the saturation, and closely compare the SSPX/NIMROD mode behavior to determine discrepancies/similarities that could lead to more efficient experimental operating regimes. This work was performed under the auspices of the US DOE by the University of California under Contract No. W-7405-ENG-48.