Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
As in other magnetic fusion devices, particle control in the spheromak is important for achieving best operation with good confinement and low radiation loss. In the Sustained Spheromak Physics eXperiment (SSPX), extensive wall conditioning (helium discharges, DC glow discharge cleaning, high temperature bakeout, and titanium gettering) has allowed us to operate at low density (j/n>1E-14 A-m), with most the plasma fueling provided by plasma flow from the coaxial helicity injector. Consequently, there is a strong increase in plasma density with injector current; the external gas fueling has only a weak effect on plasma density. Thomson scattering profile measurements show a direct correlation between plasma density and temperature (nT~constant) on all flux surfaces. Results from a new double-pulse gas injection system will be discussed. This work was performed under the auspices of US DOE by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.