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Title: The Electron Bernstein Waves Heating Project In The TJ-II Stellarator

Abstract

TJ-II is a middle sized flexible Heliac operating in Madrid, whose plasmas are created and heated by ECRH via two 300 kW gyrotrons at second harmonic X-mode (53.2 GHz). Neutral beam injection is used for second phase heating. Since the cut off density for the 2nd harmonic X-mode (n{sub c} = 1.7x10 {sup 19} m{sup -3}) is reached during NBI, EBWs are considered both for providing additional heating after NBI switch on and to perform kinetic studies in high-density plasmas. Previous work has shown that the most suitable scheme for launching EBWs in TJ-II is O-X-B mode conversion, which has acceptable heating efficiency for central densities above 1.2x10{sup 19} m{sup -3}, with an operating frequency of 28 GHz. In this work, the most relevant theoretical calculations are presented, including the relativistic effects both in ray trajectory and absorption, as well as the results of the optimization of the beam parameters that provide the maximum O-X conversion efficiency at the critical layer. A system based on a 28 GHz-100 ms diode gyrotron will be used to deliver 300 kW through a corrugated waveguide. The microwave beam is directed and focused by a steerable mirror located inside the vacuum vessel. A diagnosticmore » for measuring the EBW emission has been designed and tested on the bench. It uses a section of corrugated waveguide and a glass lens to focus the emission from the plasma into the aperture of a dual polarized quad-ridged horn. It will allow us to determine the EBW mode conversion efficiency, and also provides an indication of the electron temperature evolution in overdense plasmas.« less

Authors:
; ;  [1];  [2];  [3]
  1. Laboratorio Nacional de Fusion, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)
  2. Oak Ridge National Laboratory, Oak Ridge, TN (United States)
  3. Russian Academy of Sciences, General Physics Institute, Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
21035883
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 933; Journal Issue: 1; Conference: 17. topical conference on radio frequency power in plasmas, Clearwater, FL (United States), 7-9 May 2007; Other Information: DOI: 10.1063/1.2800508; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABSORPTION; BERNSTEIN MODE; ECR HEATING; ELECTRON TEMPERATURE; ELECTRONS; GHZ RANGE; LAYERS; MICROWAVE AMPLIFIERS; MICROWAVE RADIATION; MODE CONVERSION; NEUTRAL ATOM BEAM INJECTION; OPTIMIZATION; PLASMA; PLASMA DENSITY; PLASMA PRODUCTION; PLASMA WAVES; RELATIVISTIC RANGE; RF SYSTEMS; TJ-II HELIAC

Citation Formats

Fernandez, A, Cappa, A, Castejon, F, Caughman, J, and Tereshchenko, M. The Electron Bernstein Waves Heating Project In The TJ-II Stellarator. United States: N. p., 2007. Web. doi:10.1063/1.2800508.
Fernandez, A, Cappa, A, Castejon, F, Caughman, J, & Tereshchenko, M. The Electron Bernstein Waves Heating Project In The TJ-II Stellarator. United States. https://doi.org/10.1063/1.2800508
Fernandez, A, Cappa, A, Castejon, F, Caughman, J, and Tereshchenko, M. 2007. "The Electron Bernstein Waves Heating Project In The TJ-II Stellarator". United States. https://doi.org/10.1063/1.2800508.
@article{osti_21035883,
title = {The Electron Bernstein Waves Heating Project In The TJ-II Stellarator},
author = {Fernandez, A and Cappa, A and Castejon, F and Caughman, J and Tereshchenko, M},
abstractNote = {TJ-II is a middle sized flexible Heliac operating in Madrid, whose plasmas are created and heated by ECRH via two 300 kW gyrotrons at second harmonic X-mode (53.2 GHz). Neutral beam injection is used for second phase heating. Since the cut off density for the 2nd harmonic X-mode (n{sub c} = 1.7x10 {sup 19} m{sup -3}) is reached during NBI, EBWs are considered both for providing additional heating after NBI switch on and to perform kinetic studies in high-density plasmas. Previous work has shown that the most suitable scheme for launching EBWs in TJ-II is O-X-B mode conversion, which has acceptable heating efficiency for central densities above 1.2x10{sup 19} m{sup -3}, with an operating frequency of 28 GHz. In this work, the most relevant theoretical calculations are presented, including the relativistic effects both in ray trajectory and absorption, as well as the results of the optimization of the beam parameters that provide the maximum O-X conversion efficiency at the critical layer. A system based on a 28 GHz-100 ms diode gyrotron will be used to deliver 300 kW through a corrugated waveguide. The microwave beam is directed and focused by a steerable mirror located inside the vacuum vessel. A diagnostic for measuring the EBW emission has been designed and tested on the bench. It uses a section of corrugated waveguide and a glass lens to focus the emission from the plasma into the aperture of a dual polarized quad-ridged horn. It will allow us to determine the EBW mode conversion efficiency, and also provides an indication of the electron temperature evolution in overdense plasmas.},
doi = {10.1063/1.2800508},
url = {https://www.osti.gov/biblio/21035883}, journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 933,
place = {United States},
year = {2007},
month = {9}
}