Electron cyclotron emission from nonthermal tokamak plasmas

Harvey, R. W.; O’Brien, M.R.; Rozhdestvensky, V. V.; Luce, T. C.; McCoy, M.G.; Kerbel, G. D.

doi:10.1063/1.860530

Cited by 19 publications

(17 citation statements)

References 27 publications

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“…where K(k, θ) represents the background fluctuation electromagnetic field energy from radiations, which provides the initial amplitudes of the modes [26]. K can be calculated as…”

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confidence: 99%

“…To better validate against experiments, we also developed an ECE synthetic diagnostic code to calculate the ECE radiation power from the electron distribution [26,28]. Note that in the current model we only have the electron distribution in 2D momentum space, thus to calculate the ECE signals, we assume that the electron distribution containing runaway tail is uniform near the core from −0.5a to 0.5a (a is the minor radius), and outside this region, the electron distribution is assumed to be a Maxwellian distribution with a specified temperature profile.…”

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confidence: 99%

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Role of Kinetic Instability in Runaway-Electron Avalanches and Elevated Critical Electric Fields

Liu

Hirvijoki

et al. 2018

Phys. Rev. Lett.

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The effects of kinetic whistler wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from experiments at the DIII-D National Fusion Facility, we show that RE scattering from excited whistler waves can explain several poorly understood experimental results. We find an enhancement of the RE avalanche for low density and high electric field, but for high density and low electric field the scattering can suppress the avalanche and raise the threshold electric field, bringing the present model much closer to observations. The excitation of kinetic instabilities and the scattering of resonant electrons are calculated self-consistently using a quasilinear model and local approximation. We also explain the observed fast growth of electron cyclotron emission signals and excitation of very low-frequency whistler modes observed in the quiescent RE experiments at DIII-D tokamak. Simulations using ITER parameters show that by controlling the background thermal plasma density and temperature, the plasma waves can also be excited spontaneously in tokamak disruptions and the avalanche generation of runaway electrons may be suppressed.

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“…where K(k, θ) represents the background fluctuation electromagnetic field energy from radiations, which provides the initial amplitudes of the modes [26]. K can be calculated as…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Role of Kinetic Instability in Runaway-Electron Avalanches and Elevated Critical Electric Fields

Liu

Hirvijoki

et al. 2018

Phys. Rev. Lett.

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“…Refs. [24,25]), while kinetic treatment of stellarators requires special attention. In particular, non-thermal effects in W7-AS with specific neo-classical convective flux due to the heating of trapped electrons were studied with help of the Fokker-Planck code FPTM [26,27].…”

Section: Introductionmentioning

confidence: 99%

Ray-tracing code TRAVIS for ECR heating, EC current drive and ECE diagnostic

Marushchenko

Turkin

Maaßberg

2014

Computer Physics Communications

109

108

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A description of the recently developed ray-tracing code TRAVIS is given together with the theoretical background, results of benchmarking and examples of application. The code is written for electron cyclotron studies with emphasis on heating, current drive and ECE diagnostic. The code works with an arbitrary 3D magnetic equilibrium being applicable for both stellarators and tokamaks. The equations for ray tracing are taken in the weakly relativistic approach, i.e. with thermal effects taken into account, while the absorption, current drive and emissivity are calculated in the fully relativistic approach. For the calculation of ECCD, an adjoint technique with parallel momentum conservation is applied. The code is controlled through a specially designed graphical user interface, which allows the preparation of the input parameters and viewing the results in convenient (2D and 3D) form.

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“…is the Lorentz factor 13,[20][21][22][23] . Electron cyclotron waves emitted in the core at these frequencies can travel to the outboard plasma edge without being re-absorbed by the thermal electrons.…”

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confidence: 99%

Non-resonant destabilization of (1/1) internal kink mode by suprathermal electron pressure

Delgado‐Aparicio

Sugiyama²,

Shiraiwa

et al. 2015

Phys. Plasmas

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New experimental observations are reported on the structure and dynamics of short-lived periodic (1, 1) "fishbone"-like oscillations that appear during radio frequency heating and current-drive experiments in tokamak plasmas. For the first time, measurements can directly relate changes in the high energy electrons to the mode onset, saturation, and damping. In the relatively high collisionality of Alcator C-Mod with lower hybrid current drive, the instability appears to be destabilized by the non-resonant suprathermal electron pressure -rather than by wave-particle resonance, rotates toroidally with the plasma and grows independently of the (1, 1) sawtooth crash driven by the thermal plasma pressure. The economic feasibility of a fusion reactor can be measured in terms of β ≡ p/ B 2 /2µ 0 , where p is the plasma pressure and B 2 /2µ 0 is the magnetic field energy density. The presence of magnetohydrodynamic (MHD) instabilities can distort the orbits of fast ions and electrons compared to the equilibrium, causing an off-axis redistribution of the fusion heating and current density to the detriment of the central β, reducing the fusion power and the production of fast neutrons for tritium breeding. Therefore, understanding the stability and behavior of 3D helical modes in the core of an axisymmetric toroidal configuration remains one of the challenges of fusion research 1-6 . It is doubly significant for burning plasmas such as ITER, where the q = 1 radius that bounds these instabilities may reach half the minor radius.A helical internal kink-like mode 7-9 with dominant poloidal and toroidal mode numbers m = 1, n = 1 has recently been observed in the Alcator C-Mod tokamak 10

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Electron cyclotron emission from nonthermal tokamak plasmas

Abstract: Articles you may be interested inThermal and nonthermal electron cyclotron emission by high-temperature tokamak plasmas Rev.

Cited by 19 publications

References 27 publications

Role of Kinetic Instability in Runaway-Electron Avalanches and Elevated Critical Electric Fields

Role of Kinetic Instability in Runaway-Electron Avalanches and Elevated Critical Electric Fields

Ray-tracing code TRAVIS for ECR heating, EC current drive and ECE diagnostic

Non-resonant destabilization of (1/1) internal kink mode by suprathermal electron pressure

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