Observation of Ion Cyclotron Emission Owing to DD Fusion Product H Ions in JT-60U

Abstract

High-frequency fluctuations in the ion cyclotron range of frequency (ICRF) are excited in magnetically confined plasmas because of the distortion of velocity distribution. In deuterium plasma experiments in JT-60U, ion cyclotron emission (ICE) detected as magnetic fluctuations is observed using ICRF antennas as pickup loops. The toroidal wave-numbers can be estimated using the phase differences between the signals from antenna elements arrayed in the toroidal direction. In this manuscript, ICE due to fusion product (FP) H ions, ICE(H), which is identified separately from the second-harmonic ICE caused by D ions, is newly reported. ICE is considered to result from spontaneous excitation of magnetosonic waves associated with FP high-energy ions. ICE caused by 3 He ions and T ions has already been identified and confirmed to have finite toroidal wave-numbers. In contrast, ICE caused by ions originating in neutral beam injection has no toroidal wave-numbers. It is suggested that the appearance of ICE(H) depends strongly on the plasma density, and weak magnetic shear operation is one of the possible conditions for the observation of ICE(H).

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

“…Ion cyclotron emission (ICE) driven by energetic ions is one kind of electromagnetic radiation whose spectrum peaks correspond to the harmonics of the cyclotron frequencies of energetic ion species at the emission location. Typically, but not perpetually, ICE is observed to be excited at the outer edge of the plasma in toroidal magnetically confined fusion devices, such as JET [1,2], TFTR [3,4], JT-60U [5], ASDEX Upgrade [6], DIII-D [7], KSTAR [8,9], EAST [10] and LHD [11]; ICE from the plasma core has been described at a recent time from DIII-D [12], ASDEX Upgrade [6,[13][14][15] EAST [16] and small tokamak TUMAN-3M [17], and earlier from JT-60U [18].…”

Quantifying Fusion Born Ion Populations in Magnetically Confined Plasmas using Ion Cyclotron Emission

“…ICE is used as a diagnostic for energetic ions lost from DIII-D tokamak plasmas due to MHD activity [15]. ICE is observed from ASDEX-Upgrade [16,17] and JT-60U [18,19] tokamak plasmas, with spectral peaks at edge cyclotron harmonics of ion species that include the energetic products of fusion reactions in pure deuterium, namely protons, tritons, and helium-3 ions. ICE from sub-Alfvénic beam ions, injected at tens of keV to heat the plasma, was observed from TFTR tokamak plasmas, and is also interpreted in terms of the MCI [20].…”

Stimulated Emission of Fast Alfvén Waves within Magnetically Confined Fusion Plasmas

“…In other large magnetically confined fusion (MCF) plasmas, the corresponding energetic ion population arises either from neutral beam injection (NBI) or from trace fusion reactions, or both. For example, in the edge plasma of the ASDEX-Upgrade [15,16] and JT-60U [17,18] tokamaks, ICE is detected at the cyclotron harmonics of the proton, triton and 3 He products of fusion reactions in pure deuterium plasmas. ICE is also used as a diagnostic of lost fast ions in the DIII-D tokamak [19,20] and the large stellarator-heliotron LHD [21].…”