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Title: A High Power Helicon Antenna Design for DIII-D

A new antenna design for driving current in high beta tokamaks using electromagnetic waves, called Helicons, will be experimentally tested for the first time at power approaching 1 megawatt (MW) in the DIII-D Tokamak. This method is expected to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and may be well suited to reactor-like configurations. A low power (100 watt (W)) 476 megahertz (MHz) “comb-line” antenna, consisting of 12 inductively coupled electrostatically shielded, modular resonators, was tested in DIII-D and showed strong coupling to the plasma without disturbing its characteristics or introducing metal impurities. The high power antenna consists of 30 modules affixed to back-plates and mounted on the outer wall of the vacuum vessel above the mid-plane. The antenna design follows a similar low power antenna design modified to minimize RF loss. Heat removal is provided by water cooling and a novel heat conducting path using pyrolytic graphite sheet. The CuCrZr antenna modules are designed to handle high eddy current forces. The modules use molybdenum Faraday shields that have the plasma side coated with boron carbide to enhance thermal resistance and minimize high Z impurities. A RF strip-line feed routes the RF powermore » from coaxial vacuum feed-throughs to the antenna. Multipactor analysis of the antenna, strip line, and feedthrough will be performed. A 1.2 MW, 476 MHz klystron system, provided by the Stanford Linear Accelerator (SLAC) will provide RF power to the new antenna. Lastly, a description of the design of the high power antenna, the RF strip-line feeds, and the vessel installation will be presented.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. General Atomics, San Diego, CA (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698
Type:
Accepted Manuscript
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 72; Journal Issue: 2; Journal ID: ISSN 1536-1055
Publisher:
American Nuclear Society
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; helicon; current drive; antenna
OSTI Identifier:
1405375

Nagy, A., deGrassie, J., Moeller, C., Hansink, M., Fishler, B., Murphy, C., Pinsker, R. I., Torreblanca, H., and Tooker, J.. A High Power Helicon Antenna Design for DIII-D. United States: N. p., Web. doi:10.1080/15361055.2017.1347459.
Nagy, A., deGrassie, J., Moeller, C., Hansink, M., Fishler, B., Murphy, C., Pinsker, R. I., Torreblanca, H., & Tooker, J.. A High Power Helicon Antenna Design for DIII-D. United States. doi:10.1080/15361055.2017.1347459.
Nagy, A., deGrassie, J., Moeller, C., Hansink, M., Fishler, B., Murphy, C., Pinsker, R. I., Torreblanca, H., and Tooker, J.. 2017. "A High Power Helicon Antenna Design for DIII-D". United States. doi:10.1080/15361055.2017.1347459. https://www.osti.gov/servlets/purl/1405375.
@article{osti_1405375,
title = {A High Power Helicon Antenna Design for DIII-D},
author = {Nagy, A. and deGrassie, J. and Moeller, C. and Hansink, M. and Fishler, B. and Murphy, C. and Pinsker, R. I. and Torreblanca, H. and Tooker, J.},
abstractNote = {A new antenna design for driving current in high beta tokamaks using electromagnetic waves, called Helicons, will be experimentally tested for the first time at power approaching 1 megawatt (MW) in the DIII-D Tokamak. This method is expected to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and may be well suited to reactor-like configurations. A low power (100 watt (W)) 476 megahertz (MHz) “comb-line” antenna, consisting of 12 inductively coupled electrostatically shielded, modular resonators, was tested in DIII-D and showed strong coupling to the plasma without disturbing its characteristics or introducing metal impurities. The high power antenna consists of 30 modules affixed to back-plates and mounted on the outer wall of the vacuum vessel above the mid-plane. The antenna design follows a similar low power antenna design modified to minimize RF loss. Heat removal is provided by water cooling and a novel heat conducting path using pyrolytic graphite sheet. The CuCrZr antenna modules are designed to handle high eddy current forces. The modules use molybdenum Faraday shields that have the plasma side coated with boron carbide to enhance thermal resistance and minimize high Z impurities. A RF strip-line feed routes the RF power from coaxial vacuum feed-throughs to the antenna. Multipactor analysis of the antenna, strip line, and feedthrough will be performed. A 1.2 MW, 476 MHz klystron system, provided by the Stanford Linear Accelerator (SLAC) will provide RF power to the new antenna. Lastly, a description of the design of the high power antenna, the RF strip-line feeds, and the vessel installation will be presented.},
doi = {10.1080/15361055.2017.1347459},
journal = {Fusion Science and Technology},
number = 2,
volume = 72,
place = {United States},
year = {2017},
month = {8}
}