Initial plasmas and diamagnetic energy content in Heliotron J

This report describes the behavior of the initial plasmas in Heliotron J since July 2000. Hydrogen has been successfully produced by electron cyclotron resonance heating (ECH) (53 GHz, PECH ≤ 400 kW, Δ t ≤ 50 ms). The stored energy was measured with the diamagnetic double loops as a function of magnetic field strength (0.61 T< axis < 1.44 T). The value of Wp ≈ 0.7 kJ, which corresponds to <β> 8776; 0.2 %, was obtained by the second harmonic ECH at axis ≈ 0.95 T with the input power 400 kW, l/2π = 0.18 m and <R> axis = 1.20 m. The values of Wp ≈ 0.8 kJ and <β> ≈ 0.1 % were obtained at axis ≈ 1.44 T by the off-axis fundamental ECH. Preliminary magnetic configuration scan with the vertical field coils controls the plasma position (1.1 m < <R> axis < 1.3 m), the rotational transform, etc. The configuration effects on the energy content are discussed.