Bulk ion heating with ICRH in JET DT plasmas

Abstract

ABSTRACT.Reactor relevant ICRH scenarios have been assessed during D-T experiments on the JET tokamak using H-mode divertor discharges with ITER-like shapes and safety factors. Deuterium minority heating in tritium plasmas was demonstrated for the first time. For 9% deuterium, an ICRH power of 6 MW gave 1.66 MW of fusion power from reactions between suprathermal deuterons and thermal tritons. The Q-value of the steady state discharge reached 0.22 for the length of the RF flat top (2.7 s), corresponding to three plasma energy replacement times. The Doppler broadened neutron spectrum showed a deuteron energy of 125 keV which was optimum for fusion and close to the critical energy. Thus strong bulk ion heating was obtained at the same time as high fusion efficiency. Deuterium fractions around 20% produced the strongest ion heating together with a strong reduction of the suprathermal deuteron tail. The edge localised modes (ELMs) had low amplitude and high frequency and each ELM transported less plasma energy content

Evaluation of neutron spectrometer techniques for ITER using synthetic data

“…This effect has previously been observed, see e.g. [51]. The alpha knock on component is also included in this study [15].…”

A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

“…(b) For the JET pulse 42769, Start et al reported X Be ≈ 1.5%. It was estimated that the Be impurities were absorbing about 40% of the RF power [11]. Such a non-negligible Be heating was observed even though the IC resonance of Be impurities was located off-axis and although the used D:T ratio (X D = 18%) was quite different to the optimal values we have computed.…”

“…This scenario typically shows the best performance at minority concentrations of X mino = n mino /n e ≈ 3 − 10% and has been routinely used for plasma heating. Though minority heating has a quite strong single-pass absorption (SPA), especially for hydrogen minority heating in deuterium majority plasmas, the ratio of the left-to the right-hand polarization at the IC resonance of minority ions is limited [11] …”

“…[1,3,4,7], with the emphasis to ITER in, e.g., [8,9]. Many of these scenarios were studied experimentally during the past D-T experiments in JET and TFTR tokamaks [10][11][12][13][14]. Currently, the second harmonic heating of tritium ions (ω = 2ω cT ) is considered as the main ICRF scenario for the ITER burn-phase plasmas, and the fundamental heating of a small fraction of 3 He ions (ω = ω c, 3 He ), additionally puffed into the plasma, for the ramp-up low-temperature heating stage of the pulse.…”

“…Currently, the second harmonic heating of tritium ions (ω = 2ω cT ) is considered as the main ICRF scenario for the ITER burn-phase plasmas, and the fundamental heating of a small fraction of 3 He ions (ω = ω c, 3 He ), additionally puffed into the plasma, for the ramp-up low-temperature heating stage of the pulse. In JET, a fourfold increase of the neutron emission was observed when X[ 3 He] = 4% was injected [11].…”