Scrape-off layer ion acceleration during fast wave injection in the DIII-D tokamak

Pace, D. C.; Pinsker, R. I.; Heidbrink, W. W.; Fisher, R. K.; Zeeland, M. A. Van; Austin, M. E.; McKee, G. R.; García-Muñoz, M.

doi:10.1088/0029-5515/52/6/063019

Cited by 14 publications

(16 citation statements)

References 39 publications

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“…This will allow velocity-space studies of fast-ion distributions which are generated by up to 20 MW of neutral beam injection power and 6 MW of ion cyclotron heating power [53][54][55]. Moreover, weight functions are not specific to FIDA and have also been given for collective Thomson scattering [12], neutron count rate measurements [2], neutral particle analyzers [2], fast-ion loss detectors [56], neutron spectroscopy [57,58] and beam emission spectroscopy [59]. If weight functions for the other diagnostics are correctly scaled, as those for FIDA and CTS [12], the fast-ion diagnostics can be combined in joint measurements of 2D fast-ion velocity distribution functions using the available diagnostics [32].…”

Section: Fast Ion Studiesmentioning

confidence: 99%

On velocity-space sensitivity of fast-ion D-alpha spectroscopy

Salewski

Geiger

Moseev

et al. 2014

Plasma Phys. Control. Fusion

123

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Abstract. The velocity-space observation regions and sensitivities in fast-ion D α (FIDA) spectroscopy measurements are often described by so-called weight functions.Here we derive expressions for FIDA weight functions accounting for the Doppler shift, Stark splitting, and the charge-exchange reaction and electron transition probabilities. Our approach yields an efficient way to calculate correctly scaled FIDA weight functions and implies simple analytic expressions for their boundaries that separate the triangular observable regions in (v , v ⊥ )-space from the unobservable regions. These boundaries are determined by the Doppler shift and Stark splitting and could until now only be found by numeric simulation.

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Section: Fast Ion Studiesmentioning

confidence: 99%

On velocity-space sensitivity of fast-ion D-alpha spectroscopy

Salewski

Geiger

Moseev

et al. 2014

Plasma Phys. Control. Fusion

123

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“…While the confined energetic ion distribution should quickly become axisymmetric during the use of a single antenna, effects near the antenna can also produce energetic ions, e.g., the FILD at DIII-D recently observed acceleration of ions in the SOL originating near a single fast wave antenna. 54 At C-Mod, the J-antenna is of an advanced and unique field-aligned design that is expected to reduce parasitic edge losses, resulting in decreased impurity generation and improved performance. 55 Figure 10 shows that the FILD signal varies according to which antenna injects power into the plasma.…”

Section: Analysis and Initial Resultsmentioning

confidence: 99%

Energetic ion loss detector on the Alcator C-Mod tokamak

Pace

Granetz

Vieira

et al. 2012

Review of Scientific Instruments

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A scintillator-based energetic ion loss detector has been successfully commissioned on the Alcator C-Mod tokamak. This probe is located just below the outer midplane, where it captures ions of energies up to 2 MeV resulting from ion cyclotron resonance heating. After passing through a collimating aperture, ions impact different regions of the scintillator according to their gyroradius (energy) and pitch angle. The probe geometry and installation location are determined based on modeling of expected lost ions. The resulting probe is compact and resembles a standard plasma facing tile. Four separate fiber optic cables view different regions of the scintillator to provide phase space resolution. Evolving loss levels are measured during ion cyclotron resonance heating, including variation dependent upon individual antennae.

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“…It was claimed in Refs. 4,5 that the observed anomalous absorption of the FW energy by the SOL ions is the result of their interactions with the IC parametric quasi-mode decay instabilities 6,7 which were detected in the SOL near the antenna strap.…”

Section: Introductionmentioning

confidence: 96%

“…The bursts of poorly confined energetic ions with energy above 20 keV, which is observed regularly immediately following FW injection on DIII-D tokamak, is one of the well recognized channel of the FW energy leakage 4 . It was experimentally proved in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…It was experimentally proved in Ref. 4 that these high energy ions in DIII-D tokamak were created within the SOL. The other channel of the FW energy absorption, which also is absent within linear treatment, is a significant heating of the low energy ions in SOL 5 , which a) E-mail:vsmikhailenko@pusan.ac.kr b) E-mail: vladimir@pusan.ac.kr c) E-mail: haejune@pusan.ac.kr was found to be anisotropic with T i⊥ T i .…”

Section: Introductionmentioning

confidence: 99%

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Interaction of the fast wave with a scrape-off layer plasma in tokamaks. The ion cyclotron parametric instabilities and the anomalous heating of ions

Mikhailenko¹,

Mikhailenko²,

Lee³

2020

Preprint

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The theory of the ion cyclotron (IC) electrostatic parametric instabilities of plasma which are driven by the elliptically polarized fast wave (FW) of the finite wavelength is developed. This theory grounds on the methodology of the oscillating modes. It provides the analytical treatment of the parametric instabilities with wavelength comparable with the displacements of ions relative to electrons in FW. The growth rate of the IC quasimode decay instability, which was considered as a potential source of the generation of the high energy ions in scrape-off layer (SOL) during FW injection in tokamaks, is derived analytically for arbitrary values of the FW electric field and wavelengths of the unstable IC perturbations. The comprehensive numerical analysis of the dispersion equation for three wave system which contains the IC mode ϕ i (k i , ω) and its harmonics, where ω 0 is FW frequency, is performed. It reveals that the parametric IC instability for this wave system has the maximum growth rate for the IC waves with wavelength comparable with the thermal ion Larmor radius. It is found that the inverse electron Landau damping plays essential role in the development of this instability. The possible mechanism of the saturation of this instability is the scattering of ions by the ensemble of the IC waves with random phases, which limits the development of the instability on the high level. The anomalous heating rates of ions resulted from the interactions of ions with parametric IC turbulence is determined employing the developed quasilinear theory for the IC quasimode decay instability. The derived results reveals, that the experimentally observed anisotropic heating of cold SOL ions may be caused by the parametric IC turbulence in SOL. However, the IC parametric turbulence is unlikely to be responsible for the experimentally observed bursts of poorly confined suprathermal ions in the SOL of tokamak plasmas.

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Scrape-off layer ion acceleration during fast wave injection in the DIII-D tokamak

Cited by 14 publications

References 39 publications

On velocity-space sensitivity of fast-ion D-alpha spectroscopy

On velocity-space sensitivity of fast-ion D-alpha spectroscopy

Energetic ion loss detector on the Alcator C-Mod tokamak

Interaction of the fast wave with a scrape-off layer plasma in tokamaks. The ion cyclotron parametric instabilities and the anomalous heating of ions

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