Ion cyclotron emission studies: Retrospects and prospects

Gorelenkov, N. N.

doi:10.1134/s1063780x16050044

Cited by 18 publications

(19 citation statements)

References 54 publications

(107 reference statements)

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“…First, the values of key parameters, notably the ratio of the characteristic perpend icular velocity of the energetic ions to the local Alfvén speed. This needs to be of order unity [16][17][18][19][20][21][22][23][24][25][26][27][28]. Second, the structure of the distribution of the energetic ions in velocity space, which needs to be strongly non-Maxwellian in order to excite the MCI which underlies ICE.…”

Section: Discussionmentioning

confidence: 99%

“…Full gyro-orbit kinetics are essential for capturing cyclotron harmonic resonance effects including, as we shall see, coupling between modes driven at different harmonics by collective instability. The simulations detailed in [2,14,[23][24][25] are set up in slab geometry, hence they do not incorporate realistic toroidal geometry and the associated compressional Alfvén eigenmode structure [26][27][28][29][30]. Nevertheless this spatially localised physics approach is successful in capturing most of the observed features of ICE, including also recent results from the heliotron-stellarator LHD [31,32].…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear wave interactions generate high-harmonic cyclotron emission from fusion-born protons during a KSTAR ELM crash

et al. 2018

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The radio frequency detection system on the KSTAR tokamak has exceptionally high spectral and temporal resolution. This enables measurement of previously undetected fast plasma phenomena in the ion cyclotron range of frequencies. Here we report and analyse a novel spectrally structured ion cyclotron emission (ICE) feature in the range 500 MHz to 900 MHz, which exhibits chirping on sub-microsecond timescales. Its spectral peaks correspond to harmonics l of the proton cyclotron frequency f cp at the outer midplane edge, where l = 20-36. This frequency range exceeds estimates of the local lower hybrid frequency f LH in the KSTAR deuterium plasma. The new feature is time-shifted with respect to a brighter lower-frequency chirping ICE feature in the range 200 MHz (8f cp ) to 500 MHz (20f cp ), which is probably driven (Chapman et al 2017 Nucl. Fusion 57 124004) by 3 MeV fusion-born protons undergoing collective relaxation by the magnetoacoustic cyclotron instability (MCI). Here we show that the new, fainter, higher-frequency chirping ICE feature is driven by nonlinear wave coupling between different neighbouring spectral peaks in the lower-frequency ICE feature. This follows from bispectral analysis of the measured KSTAR fields, and of the field amplitudes output from particle-in-cell (PIC) simulations of the KSTAR edge plasma containing fusionborn protons. This reinforces the identification of the MCI as the plasma physics process underlying proton harmonic ICE from KSTAR, while providing a novel instance of nonlinear wave coupling on very fast timescales.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear wave interactions generate high-harmonic cyclotron emission from fusion-born protons during a KSTAR ELM crash

et al. 2018

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“…In addition to the pioneering papers we listed above, there were several follow-up studies that treated KTAEs in order to determine the radiative damping analytically [308,309] and numerically non-perturbatively [310,311]. One focus was on the computations of the radiative damping mechanisms that was originally derived and computed for TAEs [312].…”

Section: Kinetic Taesmentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

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The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium-tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the 'sea' of Alfvén eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

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“…If the FIDA measurements agree with synthetic FIDA measurements [21][22][23][24][25][26][27][28][29][30], it is argued that f (v , v ⊥ ) in the experiment corresponds to the simulation and that the fast-ion behavior therefore is understood -at least in the interrogation regions of the measurements. However, if they disagree [31][32][33][34][35][36][37][38][39][40][41][42], it is unclear how the experimental and simulated functions f (v , v ⊥ ) are different. In this case, we would rather solve the inverse problem to know what the measured FIDA spectra imply about f (v , v ⊥ ).…”

Section: Introductionmentioning

confidence: 99%

Measurement of a 2D fast-ion velocity distribution function by tomographic inversion of fast-ion D-alpha spectra

et al. 2014

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We present the first measurement of a local fast-ion 2D velocity distribution function f (v , v ⊥ ). To this end, we heated a plasma in ASDEX Upgrade by neutral beam injection and measured spectra of fast-ion D α (FIDA) light from the plasma centre in three views simultaneously. The measured spectra agree very well with synthetic spectra calculated from a TRANSP/NUBEAM simulation. Based on the measured FIDA spectra alone, we infer f (v , v ⊥ ) by tomographic inversion. Salient features of our measurement of f (v , v ⊥ ) agree reasonably well with the simulation: the measured as well as the simulated f (v , v ⊥ ) are lopsided towards negative velocities parallel to the magnetic field, and they have similar shapes. Further, the peaks in the simulation of f (v , v ⊥ ) at full and half injection energies of the neutral beam also appear in the measurement at similar velocity-space locations. We expect that we can measure spectra in up to seven views simultaneously in the next ASDEX Upgrade campaign which would further improve measurements of f (v , v ⊥ ) by tomographic inversion.

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Ion cyclotron emission studies: Retrospects and prospects

Cited by 18 publications

References 54 publications

Nonlinear wave interactions generate high-harmonic cyclotron emission from fusion-born protons during a KSTAR ELM crash

Nonlinear wave interactions generate high-harmonic cyclotron emission from fusion-born protons during a KSTAR ELM crash

Energetic particle physics in fusion research in preparation for burning plasma experiments

Measurement of a 2D fast-ion velocity distribution function by tomographic inversion of fast-ion D-alpha spectra

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