Final Report - Effect of Magnetic Configuration on Spheromak Performances, FY2000 - FY2001, Tracking No.00-SI-008

This is the final report on LDRD SI-funded research to determine the Effect of Magnetic Field Configurations on Spheromak Performance for the years FY2000-FY2001, during which a new set of bias magnetic field coils was used to change the vacuum magnetic field configuration of the SSPX spheromak at LLNL. The USDOE Office of Fusion Energy Science funded the routine operation of the SSPX facility during FY00 and FY01. A photo of the SSPX facility as it appeared in mid-FY01, appears in this report. The main distinctive feature of the spheromak is that currents in the plasma itself produce the confining toroidal magnetic field, rather than a complex set of external coils. The Sustained Spheromak Physics Experiment (SSPX) device was designed and built study how well the spheromak can contain plasma energy while dynamo processes in the plasma maintain the confining magnetic fields. The spheromak potentially offers advantages over other fusion reactor concepts because it is compact, has no field coils linking the vacuum vessel, and can be operated in a steady state with voltage applied to external electrodes. It is predicted that the ability of the SSPX to contain the plasma thermal energy will increase with increasing plasma electron temperature; that is, the hotter it is, the better it will work. Our near-term goal for the SSPX facility is to determine which of several magnetic field configurations works best to produce hot, well-confined spheromak plasmas. We also want to verify the predicted inverse relation between plasma temperature and heat loss, and to use these results to design an even higher-temperature follow-on experiment that will push closer to fusion conditions. New features of the SSPX spheromak include a large-radius coaxial plasma injector to improve efficiency, a conformal flux conserver to minimize open field lines around the plasma, a divertor to aid in cold-particle exhaust, and the programmable-bias magnetic field coils to vary the magnetic geometry. The effect of operating SSPX with the bias magnetic-field coils is the subject of this LDRD research project