Overview of TAE technologies’ HHFW project on LAPD

Overview of TAE Technologies’ HHFW Project on LAPD
X. Yang1, a), M. Binderbauer1, Y. Song2, T. Carter3, R. Goulding4, Q. Yang2, G. Chen2, Y. Song1, J. Schroeder1, T. DeHaas1, B. Van Compernolle3, F. Ceccherini1, L. Galeotti1, I. Allfrey1, S. Dettrick1, A. Sibley1, P. Feng1, T. Valentine1, W. Waggoner1, C. Lau4, S. Shiraiwa5, J. Wright5, N. Bertelli6, M. Ono6, W. Horton7.
1 TAE Technologies, Foothill Ranch, California, USA
2 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, P. R. China 3 University of California, Los Angeles, Los Angeles, California, USA
4 Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
5 Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 6 Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA
7 University of Texas, Austin, Texas, USA
a)Corresponding author: xyang@tae.com
Abstract. Simulation survey performed at TAE Technologies, has demonstrated that high harmonic fast wave (HHFW) heating is a promising scenario to heat core electrons of FRC plasma. To prepare the proposed experimental study of HHFW antenna-plasma coupling and wave propagation on LAPD machine at UCLA, a high-power-capable 4-strap antenna has been calculated and designed through collaboration among TAE, ORNL, ASIPP, and UCLA. This antenna was mechanically designed and fabricated by ASIPP and it has been installed recently on LAPD. Meanwhile, by using the Petra-M code, a newly developed generic electromagnetic simulation tool for modeling RF wave propagation, the RF- SciDAC team starts 3D full wave simulations. Detailed information on antenna electromagnetic simulations and mechanical design, as well as preliminary experimental results of wave propagation study with the newly installed phased- array antenna, will be presented in this paper.
INTRODUCTION
Over the past decades of field-reversed configuration (FRC) plasma research, the topic of efficient RF wave electron heating has rarely been explored. Simulation survey [1] recently performed at TAE Technologies has found for the first time that high harmonic fast wave (HHFW), which has been adapted successfully to high beta, overdense spherical tokamak (ST) for the experiments of core electron heating and off-axis current drive [2 - 4], can be also used to heat the core electrons of FRC plasmas.
Motivated by these promising simulation results, a deployment of HHFW heating has been planned on C-2W, an advanced beam-driven FRC device recently built at TAE. During the process of conceptually designing HHFW antenna, multiple technical challenges are encountered: (a) compact and limited space near the midplane of the machine, (b) fast ions’ large betatron orbits extending well outside the separatrix of the FRC plasma, and (c) possible radial or axial shifting and or shrinking of the “football-shaped” FRC plasma during the discharge. These elements create major challenges for fast waves’ launching, coupling, and propagation; as a result, HHFWs’ utility and efficiency are more unpredictable in C-2W FRC plasmas than in tokamaks or spherical tokamaks. Therefore, it is of vital importance to experimentally study HHFW antenna-plasma coupling and wave propagation on a reliable test bench equipped with sophisticated diagnostics. Our survey has found that in terms of similar machine configuration, highly reproducible plasmas, broad range of operational conditions, available ports and vessel space for a phased-
23rd Topical Conference on Radiofrequency Power in Plasmas
AIP Conf. Proc. 2254, 070002-1–070002-4; https://doi.org/10.1063/5.0013563 Published by AIP Publishing. 978-0-7354-2013-7/$30.00
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