rf Plasma Heating in a Mirror Machine at Frequencies near the Ion Cyclotron Frequency and its Harmonics

By applying 75 kW of pulsed rf power to a decaying hydrogen plasma following turbulent heating, we have maintained a plasma density of ${10}^{12}$ to 5 × ${10}^{12}$ ${\mathrm{cm}}^{-3\mathrm{}}$ for the 600-μ sec duration of the rf pulse. Neutral energy analyzer measurements of ion temperature indicate $T_i\sim 100$ eV, while diamagnetic loop measurements indicate $100 \mathrm{eV}<T_e+T_i<200\mathrm{} \mathrm{eV}$. Probe measurements made using different equipment show discrete changes in the amplitude of the rf signals near the harmonics of the ion cyclotron frequency.