Development of long-pulse heating & current drive actuators & operational techniques compatible with a high-Z divertor & first wall
- Univ. of California, San Diego, CA (United States)
This was a collaboration between UCSD and MIT to study the effective application of ion-cyclotron heating (ICRH) on the EAST tokamak, located in China. The original goal was for UCSD to develop a diagnostic that would allow measurement of the steady state, or DC, convection pattern that develops on magnetic field lines that attach or connect to the ICRH antenna. This diagnostic would then be used to develop techniques and approaches that minimize or even eliminate such DC convection during application of strong ICRH heating. This was thought to then indicate reduction or elimination of parasitic losses of heating power, and thus be an indicator of effective RF heating. The original plan to use high speed digital gas-puff imaging (GPI) of the antenna-edge plasma region in EAST was ultimately unsuccessful due to limitations in machine and camera operations. We then decided to attempt the same experiment on the ALCATOR C-MOD tokamak at MIT which had a similar instrument already installed. This effort was ultimately successful, and demonstrated that the underlying idea of using GPI as a diagnostic for ICRH antenna physics would, in fact, work. The two-dimensional velocity fields of the turbulent structures, which are advected by RF-induced E x B flows, are obtained via the time-delay estimation (TDE) techniques. Both the magnitude and radial extension of the radial electric field E-r were observed to increase with the toroidal magnetic field strength B and the ICRF power. The TDE estimations of RF-induced plasma potentials are consistent with previous results based on the probe measurements of poloidal phase velocity. The results suggest that effective ICRH heating with reduced impurity production is possible when the antenna/box system is designed so as to reduce the RF-induced image currents that flow in the grounded conducting antenna frame elements that surround the RF antenna current straps.
- Research Organization:
- Univ. of California, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- DOE Contract Number:
- SC0010593
- OSTI ID:
- 1416179
- Report Number(s):
- DOE-UCSD-SC0010593
- Resource Relation:
- Related Information: R.J. Hong, S.J. Wuktich, Y. Lin et al, Characterization of SOL plasma flows and potentials in ICRF-heated plasmas in ALCATOR C-Mod, Plasma Phys. Contr. Fusion 59 (10) 105008 (2017), doi: 10.1088/1361-6587/aa7f4b
- Country of Publication:
- United States
- Language:
- English
Characterization of SOL plasma flows and potentials in ICRF-heated plasmas in Alcator C-mod
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journal | August 2017 |
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