RF waves in nonequilibrium-plasma accelerator

An experiment was devised for measuring the intensity of oscillations in the frequency range 500-300 MHz in an electrodynamic discharge for plasma acceleration with respect to cross section and to the length of the plasma flux. It was found that the spectral energy density of the high frequency oscillations exceeds the thermal level on an order of 4-5. Phase velocities of excited waves agreed with velocities of fast electrons in the cathode region of the discharge. The mechanism of HF instability associated with fast electrons in the discharge is examined.