MHD PLASMA ACTIVITY IN THE U-3M TORSATRON DURING THE RF CLEANING MODE WITH THE MAGNETIC FIELD Bϕ(0) = 0.02 T

Abstract

In the considered mode of cleaning, plasma was created and heated by antennas at frequencies fRF1 ≈ 7.9 and fRF2 ≈ 8.8 MHz, the magnitude of the constant magnetic field was Bϕ(0) ≈ 0.02 T, so that the ion cyclotron frequency was much lower than the heating frequency. The average plasma density was n ~ 1×1018 m-3, electron temperature was ~10 eV, working gas pressure was 10-4 Torr. Using a set of 15 magnetic sensors installed in one of the poloidal sections of the torus, fluctuations of the poloidal magnetic field were recorded. It was found that in the investigated frequency range 0...100 kHz, the spectrum of fluctuations of the poloidal magnetic field has two characteristic frequencies 6 and 49 kHz. The dynamics of the intensity of the magnetic plasma fluctuations for the investigated frequencies was also studied.