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 10¹² to 5 ×{} 10¹² cm^-3 for the 600-{μ} sec duration of the rf pulse. Neutral energy analyzer measurements of ion temperature indicate Tᵢ~100 eV, while diamagnetic loop measurements indicate 100 eV<Tₑ+Tᵢ<200 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.