Experiments on Ion Cyclotron Heating of Plasma in the Heliotron-B Device

Abstract

The Heliotron magnetic field for plasma confining has many magnetic slopes suitable to cause a phase mixing of ion cyclotron waves propagating along the magnetic lines of force. Experiments on ion cyclotron heating with this mechanism were carried out by using a plasma generator “Heliotron-B”. A rf coil of Picket Fence type fed rf power into plasma and excited the ion cyclotron waves of 12cm axial wave length. Rf power absorption curves as a function of rf frequency, obtained by using a low power oscillator, showed there are two kinds of rf loading peaks of plasma ; one is due to the excitation of the ion cyclotron waves and another due to the cyclotron resonance of individual ions. The exciting efficiency of the ion cyclotron waves was above 75%. Doppler shifts of particle cyclotron reasonance from the cyclotron frequency were also observed under the Joule heating. This fact suggests that ion beams are flowing in plasma under the Joule heating. The plasma generated by the Joule heating was supplied with rf power of 100kW, and ion cyclotron waves were excited and damped in the Heliotron field. As a results, ion temperature could be raised up to 4XlO⁵°K. Electron temperature was insensible to this heating.