Ion cyclotron emission driven by deuterium neutral beam injection and core fusion reaction ions in EAST

Abstract

Ion cyclotron emissions (ICE) driven by high energy ions in the Experimental Advanced Superconducting Tokamak (EAST) are reported. The classic edge emissions driven by energetic neutral beam injection (NBI) deuterium ions at low magnetic field side, near the plasma pedestal region, are often observed. In addition, the ICE, the spectral peaks of which match the cyclotron frequencies of fusion ions and NBI deuterium ions near the magnetic axis are also detected. In ICE experiments, deuterium plasma is heated with deuterium NBI, without any ion cyclotron resonance heating. In H-mode discharges, edge localized mode can not only increase the intensity of the edge ICE, but also broaden its spectrum. ICE also appears at the time of plasma disruption in the EAST tokamak, this radiation seems to be driven by deuterium ions at the radial location of R = 1.85 m–2.05 m. These results lead to a practical way to monitor fusion alpha particles in deuterium–tritium devices such as ITER, DEMO and CFETR in the future.

Explanation of core ion cyclotron emission from beam-ion heated plasmas in ASDEX Upgrade by the magnetoacoustic cyclotron instability

“…From these four curves in figure 5 (a) and (b), it is clear that both the fundamental and the second harmonic frequencies of core ICE amplitude fall off extremely fast after the NBI turn-offs: NBI-8 (71 keV) turn-off at t = 2.208 s and NBI-3 (52 keV) turn-off at t = 2.244 s. Previously [30], it is described that the second harmonic of the core ICE excited by sub-Alfvé nic deuterium beam-injected ions disappears within 1 ms after the NBI turn-off and it is much shorter than the slowing-down time of high-energy ions. In EAST tokamak, a similar observation for the fundamental frequency of core ICE had been reported [16]. From figure 5, we also find that the ICE signal at the fundamental frequency is approximately 10 times larger than that at the second harmonic.…”

Identification of slow-wave ion cyclotron emission on JT-60U

“…ICEs in a frequency range below the bulk ion cyclotron frequency are observed in several tokamak devices, e.g. JT-60U [3], EAST [13], and ASDEX-U [14]. On JT-60U, this relatively-low-frequency ICE is observed during negative-ionsource neutral beam (N-NB) injections.…”

Development of the ion cyclotron emission diagnostic on the HL-2A tokamak

“…The ion cyclotron resonance heating (ICRH) antennas and magnetic B-dot probes are commonly used as ICE probes. They are typically used for studying the high-frequency plasma instabilities, which are mainly driven by energetic particles (EPs) [2][3][4][5]. Although the ICE is typically observed from electromagnetic emission, an electrostatic mechanism was proposed in theory [6,7].…”

“…fast ions from neutral beam injection (NBI), fusion reactions, acceleration by ICRH waves or during edge localized modes (ELMs) crash, and runaway electrons (REs) during low density discharge and major disruption. The instabilities driven by these energetic particles have been widely studied with ICE diagnostic in many devices including JET [8], TFTR [9,10], DIII-D [3,5,[11][12][13], ASDEX Upgrade [14,15], KSTAR [16][17][18] and EAST [4] tokamaks, NSTX-U [19] spherical tokamak and LHD [20] stellarator.…”

“…The common type of ICE is excited by energetic ions at the plasma edge. However, it is found that ICE instabilities can also be excited by energetic ions, most of them are driven by neutral beam ions, in the plasma core on ASDEX Upgrade [2,14], DIII-D [3] and EAST [4] recently. Whistler waves with f f ci have also been observed by this diagnostic on DIII-D for the first time [21], where f ci is the ion cyclotron frequency.…”