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Title: RF experiments in LHD

Abstract

Large Helical Device (LHD) has been started its operation from the end of March 1998. Second harmonic electron cyclotron heating (ECH) is used as a plasma production and heating. Three gyrotrons have been used at the frequency range of 84 GHz as power sources. Up to 420 kW power with the pulse length of 0.5 sec has been injected in LHD via long distance corrugated waveguide transmission system. The antenna system composed of four mirrors for each line focuses the microwave beam with the 15 mm in 1/e waist radius on the midplane of LHD in the radial direction that enables the local power deposition. The maximum stored energy with using only second harmonic ECH recorded so far is 36 kJ at the averaged density of n{sub e,ave}=1.5x10{sup 19} m{sup -3}. The maximum central electron temperature T{sub e0}=2 keV is achieved at n{sub e,ave}=3x10{sup 18} m{sup -3}. Power modulation experiments are carried out mainly to estimate the power deposition profile using ECE radiometer. The initial ICRF heating experiment was also carried out using a pair of loop antennas. The applied ICRF power is at the level of 300 kW for 0.2 sec with the frequency of 25.6 MHz. The increasemore » in the plasma stored energy was up to 13 kJ using the target plasma produced by ECH. Under the optimum H minority ratio to He, significant electron heating without any appreciable increase in the density was observed.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. National Institute for Fusion Science, Toki, 509-5292 (Japan) (and others)
Publication Date:
OSTI Identifier:
21210457
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 485; Journal Issue: 1; Conference: 13. topical conference on radio frequency power in plasmas, Annapolis, MD (United States), 12-14 Apr 1999; Other Information: DOI: 10.1063/1.59697; (c) 1999 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; ANTENNAS; ECR HEATING; ELECTRON TEMPERATURE; ELECTRONS; GHZ RANGE; ICR HEATING; ION TEMPERATURE; KEV RANGE; LHD DEVICE; MAGNETIC FIELDS; MHZ RANGE; MICROWAVE AMPLIFIERS; MIRRORS; MODULATION; PLASMA; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; RF SYSTEMS; WAVEGUIDES

Citation Formats

Kubo, S., Kumazawa, R., Shimozuma, T., Idei, H., Yoshimura, Y., Sato, M., Mutoh, T., Seki, T., Watari, T., Ohkubo, K., Takita, Y., Kobayashi, S., Ito, S., Mizuno, Y., Shinpo, F., Nomura, G., Kaneko, O., Komori, A., Yamada, H., and Ohyabu, N. RF experiments in LHD. United States: N. p., 1999. Web. doi:10.1063/1.59697.
Kubo, S., Kumazawa, R., Shimozuma, T., Idei, H., Yoshimura, Y., Sato, M., Mutoh, T., Seki, T., Watari, T., Ohkubo, K., Takita, Y., Kobayashi, S., Ito, S., Mizuno, Y., Shinpo, F., Nomura, G., Kaneko, O., Komori, A., Yamada, H., & Ohyabu, N. RF experiments in LHD. United States. doi:10.1063/1.59697.
Kubo, S., Kumazawa, R., Shimozuma, T., Idei, H., Yoshimura, Y., Sato, M., Mutoh, T., Seki, T., Watari, T., Ohkubo, K., Takita, Y., Kobayashi, S., Ito, S., Mizuno, Y., Shinpo, F., Nomura, G., Kaneko, O., Komori, A., Yamada, H., and Ohyabu, N. Mon . "RF experiments in LHD". United States. doi:10.1063/1.59697.
@article{osti_21210457,
title = {RF experiments in LHD},
author = {Kubo, S. and Kumazawa, R. and Shimozuma, T. and Idei, H. and Yoshimura, Y. and Sato, M. and Mutoh, T. and Seki, T. and Watari, T. and Ohkubo, K. and Takita, Y. and Kobayashi, S. and Ito, S. and Mizuno, Y. and Shinpo, F. and Nomura, G. and Kaneko, O. and Komori, A. and Yamada, H. and Ohyabu, N.},
abstractNote = {Large Helical Device (LHD) has been started its operation from the end of March 1998. Second harmonic electron cyclotron heating (ECH) is used as a plasma production and heating. Three gyrotrons have been used at the frequency range of 84 GHz as power sources. Up to 420 kW power with the pulse length of 0.5 sec has been injected in LHD via long distance corrugated waveguide transmission system. The antenna system composed of four mirrors for each line focuses the microwave beam with the 15 mm in 1/e waist radius on the midplane of LHD in the radial direction that enables the local power deposition. The maximum stored energy with using only second harmonic ECH recorded so far is 36 kJ at the averaged density of n{sub e,ave}=1.5x10{sup 19} m{sup -3}. The maximum central electron temperature T{sub e0}=2 keV is achieved at n{sub e,ave}=3x10{sup 18} m{sup -3}. Power modulation experiments are carried out mainly to estimate the power deposition profile using ECE radiometer. The initial ICRF heating experiment was also carried out using a pair of loop antennas. The applied ICRF power is at the level of 300 kW for 0.2 sec with the frequency of 25.6 MHz. The increase in the plasma stored energy was up to 13 kJ using the target plasma produced by ECH. Under the optimum H minority ratio to He, significant electron heating without any appreciable increase in the density was observed.},
doi = {10.1063/1.59697},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 485,
place = {United States},
year = {1999},
month = {9}
}