[Table of Contents]

Plasma and Fusion Research

Volume 8, 2402143 (2013)

Regular Articles

Design of Off-Midplane Launcher (LH3) Based on Velocity Space Synergy for Alcator C-Mod
Syun'ichi SHIRAIWA, Seung Gyou BAEK, Paul T. BONOLI, Ian FAUST, Julien HILLAIRET1), Orso MENEGHINI2), Ronald R. PARKER, Gregory M. WALLACE, James R. WILSON3), Robert W. HARVEY4) and Alexander P. SMIRNOV5)
Plasma Science Fusion Center, MIT, MA, 02139, USA
1)
CEA, IRFM, F-13108 Saint Paul-lez-Durance, France
2)
Oak Ridge Associated Universities, Oak Ridge, Tennessee, USA
3)
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
4)
CompX, Del Mar, California 92014, USA
5)
M.V. Lomonosov Moscow State University, Moscow, Russia
(Received 10 December 2012 / Accepted 13 April 2013 / Published 15 November 2013)

Abstract

A new LH launcher (LH3) is designed for Alcator C-Mod to increase the net LHCD power to 2MW. With the existing launcher (LH2), LH3 aims to enhance the single pass power absorption to improve LHCD efficiency at high density. For this purpose, launcher design parameters are surveyed to maximize the synergistic effect between LH2. Ray-tracing is extensively used and the launcher location and the launched N|| = c/v|| are optimized. At the line averaged density of 1.4×1020 m−3, it is predicted that the combination of two launchers can reduce the parasitic edge loss dramatically, and therefore can increase the LH driven current by about 50 - 60 % compared to cases in which two launchers are used separately. Based on the parameter survey, an off-midplane launcher (LH3) is designed to be located 15 cm above mid-plane. LH3 employs 8-way power splitters to improve the antenna-plasma coupling. The antenna-plasma coupling simulation is performed using COMSOL and ALOHA codes, predicting 90 % of RF power coupling when the launcher front density is high enough (≥ncutoff).

Keywords

tokamak, RF modeling, lower hybrid current drive

DOI: 10.1585/pfr.8.2402143

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This paper may be cited as follows:

Syun'ichi SHIRAIWA, Seung Gyou BAEK, Paul T. BONOLI, Ian FAUST, Julien HILLAIRET, Orso MENEGHINI, Ronald R. PARKER, Gregory M. WALLACE, James R. WILSON, Robert W. HARVEY and Alexander P. SMIRNOV, Plasma Fusion Res. 8, 2402143 (2013).