Application of the intermediate frequency range fast wave to the JIPP TII-U plasma

Abstract

A series of experiments has been conducted on the JIPP TII-U tokamak since 1989, using the newly constructed 130 MHz radiofrequency system. It has been predicted theoretically that the fast wave in this frequency range interacts weakly with particles. Two mechanisms of wave absorption have been identified in the experiment: electron Landau damping/transit time damping and 3rd harmonic ion cyclotron heating. The former mechanism is intimately connected with fast wave current drive and the latter can provide a new regime of plasma heating or a possible method of controlling the transport of alpha particles. It is found that the efficiency of the 3rd harmonic ion cyclotron heating is improved by using it in combination with neutral beam injection and ion cyclotron range of frequency heating. The heating efficiency obtained is as high as that of conventional heating. The experimental results are also analysed on the basis of a global wave theory which takes into account wave-particle interactions. These mechanisms of interaction are competing with each other; this will also be the case under more realistic reactor conditions.

Measurements of fast-ion acceleration at cyclotron harmonics using Balmer-alpha spectroscopy

“…The weight function W ϕ is proportional to the range of gyroangles that can contribute to this energy bin, W ϕ ∝ |ϕ max − ϕ min |. The range of gyroangles is readily calculated using equation (2). The final factor that contributes to the FIDA weight function is the probability of a chargeexchange reaction that converts a fast ion into a neutral in the n = 3 energy level, W cx .…”

“…Injected beam ions have been accelerated by ion cyclotron heating (ICH) at cyclotron harmonics in many tokamaks [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Most measurements of acceleration by ICH have employed neutral particle analysis [18,19], although fusion reaction measurements of neutrons and charged fusion products are also common [19,20].…”

High harmonic ion cyclotron heating in DIII-D: Beam ion absorption and sawtooth stabilization

“…At JET, strong third harmonic acceleration of (initially) thermal deuterium ions was observed [3]. Beam ion acceleration during combined beam injection and third harmonic ICRF heating was measured on JIPP TII-U [4], JT-60 [5] and TEXTOR [6,7], while fourth harmonic heating of beam ions was briefly studied on JT-60 [5] and JET [8]. Hydrogen beam ions were accelerated by second, third and fourth harmonic heating at JT-60U, but second harmonic heating was most efficient [9].…”