Session 7P - Plasma Applications and Plasma Technology.
POSTER session, Thursday morning, November 14
Exhibit Hall - Concourse Level, Adam's Mark
Helicon waves have been shown to efficiently produce high density (10^13 cm^-3) plasmas with electron temperatures of 3-5 eV for neutral gas pressures of 1-10 mtorr. The neutral pressure was found to decrease by a factor of 1/10 during the helicon disharge. Operating conditions were 200-700 W, 1000 Gauss applied field, in an argon plasma. The presence of neutral pumping indicates that axial variation in plasma properties must exist. Neutral pressure measurements indicate that the neutral pumping decreases close to the axial boundaries, together with corresponding changes in plasma properties such as density and temperature at the ends of the discharge. The plasma radiation loss has been measured for several axial locations using a photodiode in order to compare the relative radiation losses in the neutral pumping region and the end regions. At the ends of the discharge, radiative flux increased with power at a greater rate than plasma density or temperature. The radiation flux also increased with neutral pressure. The radiation flux was found to be higher at the ends than in the fully ionized center, indicating increased neutral line radiation losses at the source ends. Funded by National Science Foundation Grant No. ECS-9120326