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Title: Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U)

Abstract

A reflector for electron cyclotron resonant heating on the Tandem Mirror Experiment Upgrade has been designed to convert the high-power TE/sub 01/ output of the circular waveguide system into a linearly polarized gaussian intensity pattern in the plasma. The reflector is a computer-generated holographic optical element with a twist polarizer. Its design, fabrication, and performance are discussed. Results of the low- and high-power tests are presented. Low-power tests were used to determine the beam pattern and the degree of cross-polarization. High-power tests verified that arcing across the grooves of the twist polarizer does not occur.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (USA); TRW, Inc., Redondo Beach, CA (USA)
OSTI Identifier:
5453377
Report Number(s):
UCRL-89236; CONF-831203-20
ON: DE84003740
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 10. symposium on fusion engineering, Philadelphia, PA, USA, 5 Dec 1983
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ECR HEATING; HOLOGRAPHY; TMX DEVICES; POLARIZATION; REFLECTION; WAVEGUIDES; HEATING; HIGH-FREQUENCY HEATING; MAGNETIC MIRRORS; OPEN PLASMA DEVICES; PLASMA HEATING; TANDEM MIRRORS; THERMONUCLEAR DEVICES; 700102* - Fusion Energy- Plasma Research- Diagnostics; 700101 - Fusion Energy- Plasma Research- Confinement, Heating, & Production

Citation Formats

Coffield, F.E., Felker, B., Gallagher, N.C. Jr., Pedrotti, L.R., Stallard, B.W., Sweeney, D.W., Wyman, E.W., and Christensen, T.E. Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U). United States: N. p., 1983. Web.
Coffield, F.E., Felker, B., Gallagher, N.C. Jr., Pedrotti, L.R., Stallard, B.W., Sweeney, D.W., Wyman, E.W., & Christensen, T.E. Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U). United States.
Coffield, F.E., Felker, B., Gallagher, N.C. Jr., Pedrotti, L.R., Stallard, B.W., Sweeney, D.W., Wyman, E.W., and Christensen, T.E. Mon . "Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U)". United States. doi:. https://www.osti.gov/servlets/purl/5453377.
@article{osti_5453377,
title = {Polarizing holographic reflector for electron cyclotron resonant heating (ECRH) on the Tandem Mirror Experiment Upgrade (TMX-U)},
author = {Coffield, F.E. and Felker, B. and Gallagher, N.C. Jr. and Pedrotti, L.R. and Stallard, B.W. and Sweeney, D.W. and Wyman, E.W. and Christensen, T.E.},
abstractNote = {A reflector for electron cyclotron resonant heating on the Tandem Mirror Experiment Upgrade has been designed to convert the high-power TE/sub 01/ output of the circular waveguide system into a linearly polarized gaussian intensity pattern in the plasma. The reflector is a computer-generated holographic optical element with a twist polarizer. Its design, fabrication, and performance are discussed. Results of the low- and high-power tests are presented. Low-power tests were used to determine the beam pattern and the degree of cross-polarization. High-power tests verified that arcing across the grooves of the twist polarizer does not occur.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 14 00:00:00 EST 1983},
month = {Mon Nov 14 00:00:00 EST 1983}
}

Conference:
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  • Development of high-power components for electron cyclotron resonant heating (ECRH) applications requires extensive testing. In this paper we describe the high-power testing of various circular waveguide components designed for application on the Tandem Mirror Experiment-Upgrade (TMX-U). These include a 2.5-in. vacuum valve, polarizing reflectors, directional couplers, mode converters, and flexible waveguides. All of these components were tested to 200 kW power level with 40-ms pulses. Cold tests were used to determine field distribution. The techniques used in these tests are illustrated. The new high-power test facility at Lawrence Livermore National Laboratory (LLNL) is described and test procedures are discussed. Wemore » discuss the following test results: efficiency at high power of mode converters, comparison of high power vs low power for waveguide components, and full power tests of the waveguide system. We also explain the reasons behind selection of these systems for use on TMX-U.« less
  • We present a brief history of TMX-U's electron cyclotron resonant heating (ECRH) progress. We emphasize the 2-year performance of the system, which is composed of four 200-kW pulsed gyrotrons operated at 28 GHz. This system uses WR42 waveguide inside the vacuum vessel, and includes barrier windows, twists, elbows, and antennas, as well as custom-formed waveguides. Outside the TMX-U vessel are directional couplers, detectors, elbows, and waveguide bends in WR42 rectangular waveguide. An arc detector, mode filter, eight-arm mode converter, and water load in the 2.5-in. circular waveguide are attached directly to the gyrotron. Other specific areas discussed include the operationalmore » performance of the TMX-U pulsed gyrotrons, windows and component arcing, alignment, mode generation, and extreme temperature variations. Solutions for a number of these problems are described.« less
  • This paper will describe changes to the previously reported Electron Cyclotron Resonant Heating (ECRH) circular waveguide systems that deliver power to the Tandem Mirror Experiment Upgrade (TMX-U) machine. Four gyrotrons and associated waveguide systems, operating at 28-GHz and 200 kW each, helped establish electrostatic plugging in the end cells of TMX-U. A fifth gyrotron has been installed to power two resonant locations in the end plugs. This system and the pair of 10 kG heaters now use a slot radiator to obtain a more uniform coverage of the plasma. In addition, four 18-GHz ECRH systems have been added to themore » machine. 3 refs., 7 figs.« less
  • This paper describes control of gyrotron microwave energy output by modulation of gyrotron anode voltage. At present, Electron Cyclotron Resonant Heating (ECRH) uses five gyrotrons on the Tandem Mirror Experiment-Upgrade (TMX-U) for plasma heating. One is in the 10 kG region of each end plug, one at the 5 kG region of each end plug, and one is used for central-cell heating. Also described are the design and operation of the anode modulation system. The operating advantages of gyrotron anode modulation include power balance, independent control of each gyrotron, an ability to modulate microwave output power up to 50 kHz,more » and gyrotron tuning. The performance results of anode modulation will be discussed. 9 figs.« less
  • The TMX-U ECRH System underwent many extensive changes during the last two years of physics operations. These changes included extensive use of fiber optics and computer control to add flexibility to the system and eliminate noise problems, upgrades to Varian Model VGA-8050M long pulse gyrotron tubes, the addition of gyrotron anode-modulation for better control of individual gyrotrons, and the installation of a fifth gyrotron socket that was used to simultaneously heat both the east and west inner 10 KG locations. This paper discusses the different modifications made to the system and their effects on the overall performance of the entiremore » ECRH system. The paper also discusses the system as it presently exists and possible modifications that would be made if the future modifications were to be performed. 3 refs., 2 figs.« less