Characteristics of the three-half-turn-antenna-driven RF discharge in the Uragan-3M torsatron

In the ℓ = 3 Uragan-3M torsatron hydrogen plasma is produced by RF fields in the Alfvén range of frequencies (ω ≤ ω ci ). The initial (target) plasma with the line-averaged density of units 10 12 cm −3 is produced by a frame antenna with a broad spectrum of generated parallel wavenumbers. After this, to heat the plasma and bring its density to ~10 13 cm –3 , another, shorter wavelength three-half-turn antenna with large transverse currents is used. The behavior of the density, electron temperature, and loss of the plasma supported by the three-half-turn antenna is studied depending on the RF power fed to the antenna and initial values of the density and electron temperature supplied by the frame antenna.