Refractive and relativistic effects on ITER low field side reflectometer design

Wang, G.; Rhodes, T. L.; Peebles, W. A.; Harvey, R. W.; Budny, R.

doi:10.1063/1.3478632

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…The refraction effects associated with the plasma geometry can be treated separately without changing the main conclusion of the turbulence effects on the beam broadening. The effects of the refraction and of the plasma curvature on the microwave propagation in ITER are described, in particular, in [16]. Due to the use of the O-mode propagating in a direction almost perpendicular to the external magnetic field, which is typical for the first harmonic ECRH experiments in toroidal machines, the magnetic field plays no role in the wave propagation.…”

Section: Beam Spatial and Angular Broadening In The Frame Of The Eiko...mentioning

confidence: 99%

Electron cyclotron resonance heating beam broadening in the edge turbulent plasma of fusion machines

et al. 2015

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Two analytical models for the ordinary mode propagating through a turbulent inhomogeneous edge plasma layer are developed based on the eikonal perturbation method and weak turbulence theory approach. Simple analytical expression for a diffusion-like angular beam width variation is obtained by both methods in the case of long scale density perturbations. The predictions for the spatial beam width are benchmarked against timeaveraged results coming from the 2D Maxwell's equations solver for different turbulence k-spectra and plasma conditions. The strong (more than twofold) increase of the microwave beam angular and spatial width after crossing the turbulent edge is predicted at realistic parameters for ECRH experiments at ITER.

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Section: Beam Spatial and Angular Broadening In The Frame Of The Eiko...mentioning

confidence: 99%

Electron cyclotron resonance heating beam broadening in the edge turbulent plasma of fusion machines

et al. 2015

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“…Time dependence is modelled to include plasma formation, termination and transients such as magnetic field diffusion and sawtooth effects. PTRANSP ITER predictions are being used for various applications such as designing diagnostics [5][6][7], and for use in theory studies of Alfvén eigenmodes [8].…”

Section: Introductionmentioning

confidence: 99%

Alpha heating in ITER L-mode and H-mode plasmas

Budny

2011

Nucl. Fusion

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Predictions of alpha heating in ITER L-mode and H-mode DT plasmas are generated using the PTRANSP code. The baseline toroidal field (5.3 T), plasma current ramped to 15 MA and a flat electron density profile ramped to Greenwald fraction 0.85 are assumed. Various combinations of external heating by negative ion neutral beam injection, ion cyclotron resonance and electron cyclotron resonance are assumed to start half-way up the density ramp with the full power planned (P ext = 73 MW). 50 s later the power is reduced to 50 MW to increase Q DT, and to prevent excessive heat flow to the divertor and walls as the alpha heating increases. The time evolution of plasma temperatures and bulk toroidal rotation v ϕ are predicted assuming GLF23 and boundary parameters. Conservatively low temperatures (≃0.6 keV) and v ϕ ≃ 400 rad s−1 at the boundary (r/a ≃ 0.85) are assumed. Alternative options are used to predict v ϕ and the flow-shearing rates induced by the neutral beam torques in order to assess effects of uncertainties. Option 1 assumes the momentum transport coefficient χϕ is half the energy transport coefficient χi predicted consistently with the GLF23-predicted temperatures. With this assumption flow shearing does not have large effects on the energy transport, plasma temperatures and alpha heating. Option 2 uses GLF23 to predict v ϕ directly. Higher flow-shearing rates and alpha heating powers are predicted for heating mixes with neutral beam heating. If the L → H power threshold is twice the ITPA fit then the heating mixes with the highest neutral beam power (and the most alpha heating) transition to H-mode during the density ramp. Other heating mixes remain in L-mode. Predictions of H-mode temperatures and alpha heating depend sensitively on the assumed pedestal pressures. A scan in pedestal pressures is presented using the more pessimistic option 1. A linear increase in alpha heating with pedestal temperature and pressure is predicted.

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Analysis of the ITER low field side reflectometer employing the Beam Tracing Method

Stegmeir

Poli

Strumberger

2011

Fusion Engineering and Design

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The Beam Tracing Method, which describes electromagnetic wave propagation in the short wavelength limit including diffraction effects, is applied to microwave reflectometry. The torbeam code has been augmented with relativistic corrections to the electron mass -which are necessary for a reliable description in high temperature plasmas such as in ITER, and a beam coupling model for the receiving antenna coupling. The propagation and reception behaviour of reflectometer probe beams in the ITER geometry is computed. The received power is affected by the intensity of the beams, the offset of the beams respectively to the receiver antenna and the angle of incidence. Using a magnetic field derived from a 3D equilibrium it is shown that the effects of toroidal field ripple in ITER on the beam propagation are negligible. Various antenna configurations for the ITER low field side reflectometer are proposed and analyzed, particularly their sensitivity to plasma height variations.

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Refractive and relativistic effects on ITER low field side reflectometer design

Cited by 4 publications

References 12 publications

Electron cyclotron resonance heating beam broadening in the edge turbulent plasma of fusion machines

Electron cyclotron resonance heating beam broadening in the edge turbulent plasma of fusion machines

Alpha heating in ITER L-mode and H-mode plasmas

Analysis of the ITER low field side reflectometer employing the Beam Tracing Method

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