Evaluation of the local heat conductivity coefficient by power-modulated electron cyclotron heating in the Wendelstein VII-A Stellarator

Hartfuß, H. J.; Maaßberg, H.; Tutter, M.

doi:10.1088/0029-5515/26/5/014

Cited by 39 publications

(18 citation statements)

References 3 publications

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“…Measurements of the emission intensity as a function of frequency during the plasma discharge indicated a peaking of the emission at the lower frequencies of the spectrum, indicative of non-thermal emission. Similar measurements of non-thermal emission during ECH were also reported in Wendelstein VII-A [12]. For IMS, when the power was reduced to 15% or when plasma guns rather than ECH were used to create the discharge, peaking at the lower frequencies was no longer observed.…”

Section: Experimental Measurementssupporting

confidence: 80%

Radiofrequency plasma breakdown in a modular stellarator

Talmadge

Anderson

1988

Nucl. Fusion

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The breakdown of a hydrogen plasma using RF heating has been studied in a modular stellarator. The time delay between the beginning of an RF pulse and the production of a measurable density is examined as a function of puff pressure, RF power and magnetic field strength. The confinement time of the ionizing electrons is found to be independent of the collision frequency and their scaling is inversely proportional to the square root of the applied power. The ionization coefficient peaks when the electron cyclotron resonant layer coincides with a saddle point in the magnetic field on the outside of the torus, in agreement with a simple model for the heating rate. Under this condition, the electron cyclotron emission during the discharge is greater by an order of magnitude than when the resonant layer coincides with the magnetic axis. Application of approximately 100 W of power in the ion cyclotron range of frequencies in conjunction with electron cyclotron heating is shown to improve the confinement of the ionizing electrons by about 70%.

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Section: Experimental Measurementssupporting

confidence: 80%

Radiofrequency plasma breakdown in a modular stellarator

Talmadge

Anderson

1988

Nucl. Fusion

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“…. A more general method is the fast Fourier transform based technique (FFT) [20] , and the electron's heat diffusivity can be evaluated from the phase velocity and amplitude profile of the perturbation. ECE measurement is an ideal tool for the electron's transport study, since it can provide the evolution of electron temperature profile with a fairly good spatial and temporal resolution.…”

Section: Electron Heat Transportmentioning

confidence: 99%

Present Status of the Electron Cyclotron Emission Measurements on HT-7 and EAST

Liu¹,

Ti²,

Han³

et al. 2011

Plasma Sci. Technol.

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Present status of the diagnostics for electron cyclotron emission measurements on both HT-7 and EAST is reported. A 16-channel heterodyne radiometer system and a 20-channel grating polychromator, have been installed on HT-7 and EAST. A 32-channel heterodyne radiometer system, with a wider frequency coverage and better spatial resolution, is being built. In order to provide a reliable electron temperature profile, an in-situ absolute calibration system is currently being built. With the ECE measurements, study on the electron heat transport and the anomalous Doppler resonance is conducted.

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“…There are different diagnostics capable of measuring this temperature response, e.g. the electron cyclotron emission (ECE) diagnostic [1,3] and the soft X-ray array [2]. In this paper, however, we employ a fast bolometer system at WEGA for this purpose.…”

Section: Introductionmentioning

confidence: 99%