Recent results of LH experiments on the JT-60 tokamak

Abstract

Recent lower hybrid current drive(LHCD), and heating(LHH) experiments on JT-60 are reported. The current drive product of KeRpI~p -12.5~10~~m-*MA was achieved at the LH power of -4.5MW, and the CD efficiency, the energy confinement, the global power balance and the heat load on divertor plates were investigated in high power LHCD plasmas. Nearly steady state H-mode discharges were found during LHCD with two different frequency injections. Sawtooth suppression in NB heated plasmas by LHCD have shown an improvement in confinement near the plasma center. Parametric instabilities in LH heating experiments were significantly reduced by increasing the plasma current, and the stored energy increased linearly with heating power of up to -9MW at iTe -7 ~1 0 ? ~m -~ and Ip = 2.75MA. Parametric instabilities near the plasma edge in the ion heating regime were also reduced in peaked density plasmas produced by pellet injection, and LH waves increased the central plasma pressure at n,(O) > 1.4 x 1020m-3.

An ITER-relevant passive active multijunction launcher for lower hybrid current drive in JET-grade plasmas

“…Clearly, this concept permits the greatest flexibility and speed in the control of the N || spectrum, as each waveguide in the array is fed independently in phase, allowing for the celebrated wide N || flexibility of grills; additionally, it affords high directivities η P > 80%. Naturally, many of the LH systems developed thus far were based on the grill [2,6,12,22,[133][134][135][136][137].…”

“…In fact, LH waves a This paper is dedicated to the memory of Philippe Bibet who initiated and coordinated this project which, without his strong drive, enthusiasm and support, would not have been possible. have been driving plasma currents non-inductively since the early 1980s [1][2][3] with efficiencies well above other auxiliary systems, and with uses extending to heating of both ions [4][5][6][7][8] and electrons [9][10][11][12][13], plasma current start-up [14][15][16], ramp-up [17][18][19] and sustainment [14,20,21], control of the current profile [19,22] and of magnetohydrodynamic (MHD) activity such as sawteeth and neoclassical tearing modes (NTMs) [6,19,22,23]. In addition to its past (and still present) applications, LHCD has been demonstrated to be a crucial actuator in the improved confinement regimes that have become collectively known as the advanced tokamak (AT).…”