Fast polarizers installation for ECRH and ECE in TCV

Silva, Miguel; Goodman, T.; Felici, F.; Porte, L.

doi:10.1016/j.fusengdes.2011.01.043

Cited by 7 publications

(3 citation statements)

References 17 publications

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“…This antenna allows poloidal (5 • -50 • ) and toroidal (−180 • to 180 • ) steering of the beam with 0.2 • accuracy. This launcher system also features a pair of polariser miter bends [36] housed inside an oversized corrugated circular waveguide [37]. The polariser miter bends allow coupling of the diagnostic output beam into either O or X-mode polarisations in a wide range of plasma scenarios [38].…”

Section: Spr Diagnostic Descriptionmentioning

confidence: 99%

High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak

Cabrera

Labit

Coda

et al. 2021

Plasma Phys. Control. Fusion

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This publication presents high spatio-temporal resolution (mm µs −1 ) density profile measurements of the pedestal top during type I, III, and small edge localized mode (ELM) H-mode plasmas in the tokamak à configuration variable (TCV). These measurements were performed using a novel short-pulse reflectometer. Average inter-ELM density profiles are obtained via conditional averaging using the D α trace as ELM indicator. Changes to the pedestal density profile gradients prior to type-III ELMs reveal unique pedestal dynamics leading to the ELM crash which can provide important experimental data for validation of non-linear MHD ELM simulations. The small-ELM scenario is found to feature a ∼25-35 kHz quasi-coherent density fluctuation near the separatrix ρ ψ ∼ 0.993-1.05 not observed during a similar type-I ELM discharge. This oscillation is also found in low-field-side magnetic pick-up probes displaying a ballooning character and n = +1 toroidal mode number. This oscillation could help explain the markedly different pedestal dynamics observed in the small-ELM regime.

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Section: Spr Diagnostic Descriptionmentioning

confidence: 99%

High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak

Cabrera

Labit

Coda

et al. 2021

Plasma Phys. Control. Fusion

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show abstract

“…Figure 3 shows two such polarizer miter bends in series (a polarization rotator and circular polarizer) that can produce any arbitrary output elliptical polarization when fed a linear polarization 12 . These polarizers had already been used in TCV for ECRH and oblique ECE applications; further technical details can be found elsewhere 13 . The ECPOL 14 suite is used to optimize both polarizer angles for the best possible transmission of a particular linear polarization in the telescope to a target arbitrary elliptical polarization in the plasma.…”

Section: The Launcher Antenna and Signal Pathmentioning

confidence: 99%

V-band Doppler backscattering diagnostic in the TCV tokamak

Cabrera

Coda

Porte

et al. 2018

Review of Scientific Instruments

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A variable configuration V-band heterodyne Doppler back-scattering diagnostic has been recently made operational in the tokamak configuration variable. This article describes the hardware setup options, flexible quasi-optical launcher antenna, data-analysis techniques, and first data. The diagnostic uses a fast arbitrary waveform generator as the main oscillator and commercial vector network analyzer extension modules as the main mm-wave hardware. It allows sweepable single or multi-frequency operation. A flexible quasi-optical launcher antenna allows 3D poloidal (10°-58°) and toroidal (-180° to 180°) steering of the beam with 0.2° accuracy. A pair of fast HE miter-bend polarizers allow flexible coupling to either O or X mode and programmable polarization changes during the shot. These have been used to measure the magnetic-field pitch angle in the edge of the plasma by monitoring the backscattered signal power. Ray-tracing simulations reveal an available k range between 3 and 16 cm with a resolution of 2-4 cm. Perpendicular rotation velocity estimates compare well against ExB plasma poloidal rotation estimates from charge exchange recombination spectroscopy.

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“…Electron cyclotron resonance heating (ECRH), as an effective core heating tool, has been a well-established approach in tokamak magnetic confinement devices [1][2][3]. Usually, the EC power is launched as narrow Gaussian beams, which gives rise to highly localized power deposition at the cyclotron resonance layer.…”

Section: Introductionmentioning

confidence: 99%

Plasma heating by electron cyclotron wave and the temperature effects on lower hybrid current drive on EAST

Xu²,

Wang³

et al. 2023

Nucl. Fusion

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This paper presents the progress in the long - pulse operation of the electron cyclotron (EC) system and the achievements in high - electron temperature plasmas by the combined EC and lower hybrid (LH) waves heating since the EC system was built in 2015. An electron temperature of up to 12 keV with a duration over 100 s was realized by the simultaneous heating of EC and LH waves at the line-averaged density n ̅_e ~ 1.8 *10^19/m^3. The plasma heating effect strongly depends on the location of EC power deposition. H-mode plasmas with solely EC wave auxiliary heating have been obtained on EAST for the first time. These H-mode discharges show an enhanced confinement factor H98(y,2) around 1.0, which is higher than the previous H-mode using LH power alone [G.S. Xu et al Nucl. Fusion 51 (2011) 072001]. The total heating power is very close to the threshold value for L-H transition according to the international tokamak scaling. In addition to the temperature effects inside the separatrix, higher electron temperature produced by EC wave is found to reduce the LH power loss in the scrape-off layer (SOL) due to collisional absorption, which is beneficial to further increase the lower hybrid current drive (LHCD) efficiency. Ray-tracing/Fokker-Planck modeling results indicate that higher electron temperature can shorten the LH wave propagation on EAST in a multiple-pass regime, thus decreasing the collisional dissipation.

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Fast polarizers installation for ECRH and ECE in TCV

Cited by 7 publications

References 17 publications

High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak

High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak

V-band Doppler backscattering diagnostic in the TCV tokamak

Plasma heating by electron cyclotron wave and the temperature effects on lower hybrid current drive on EAST

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