TITLE

Absorption of lower hybrid waves in the scrape off layer of a diverted tokamak

AUTHOR(S)
Wallace, G. M.; Parker, R. R.; Bonoli, P. T.; Hubbard, A. E.; Hughes, J. W.; LaBombard, B. L.; Meneghini, O.; Schmidt, A. E.; Shiraiwa, S.; Whyte, D. G.; Wright, J. C.; Wukitch, S. J.; Harvey, R. W.; Smirnov, A. P.; Wilson, J. R.
PUB. DATE
August 2010
SOURCE
Physics of Plasmas;Aug2010, Vol. 17 Issue 8, p082508
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The goal of the Lower Hybrid Current Drive (LHCD) system on the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] is to investigate current profile control under plasma conditions relevant to future tokamak experiments. Experimental observations of a LHCD “density limit” for C-Mod are presented in this paper. Bremsstrahlung emission from relativistic fast electrons in the core plasma drops suddenly above line averaged densities of 1020 m-3 (ω/ωLH∼3–4), well below the density limit previously observed on other experiments (ω/ωLH∼2). Electric currents flowing through the scrape off layer (SOL) between the inner and outer divertors increase dramatically across the same density range that the core bremsstrahlung emission drops precipitously. These experimental x-ray data are compared to both conventional modeling, which gives poor agreement with experiment above the density limit and a model including collisional absorption in the SOL, which dramatically improves agreement with experiment above the observed density limit. These results show that strong absorption of LH waves in the SOL is possible on a high density tokamak and the SOL must be included in simulations of LHCD at high density.
ACCESSION #
53421748

 

Related Articles

  • Lower hybrid current drive efficiency at high density on Tore Supra. Goniche, M.; Sharma, P. K.; Basiuk, V.; Baranov, Y.; Castaldo, C.; Cesario, R.; Decker, J.; Delpech, L.; Ekedahl, A.; Hillairet, J.; Kirov, K.; Mazon, D.; Oosako, T.; Peysson, Y.; Prou, M. // AIP Conference Proceedings;12/23/2011, Vol. 1406 Issue 1, p407 

    No abstract available.

  • Lower hybrid current drive in a high density diverted tokamak. Wallace, G. M.; Hubbard, A. E.; Shiraiwa, S.; Bonoli, P. T.; Faust, I. C.; Harvey, R. W.; Hughes, J. W.; LaBombard, B. L.; Lau, C.; Meneghini, O.; Parker, R. R.; Reinke, M. L.; Schmidt, A. E.; Smirnov, A. P.; Terry, J. L.; Whyte, D. G.; Wilson, J. R.; Wright, J. C.; Wukitch, S. J. // AIP Conference Proceedings;12/23/2011, Vol. 1406 Issue 1, p419 

    Experimental observations of LHCD at high density (ne>1020m∼3) on the Alcator C-Mod tokamak are presented in this paper. Bremsstrahlung emission from relativistic fast electrons in the core plasma drops sharply in single null discharges well below the density limit previously observed on...

  • Plasma density fluctuations measurements by heavy ion beam probe with a multiple cell array detector on the tokamak ISTTOK. Nedzelskiy, I.; Silva, C.; Alves, D.; Coelho, R.; Fernandes, H. // Plasma Physics Reports;Oct2009, Vol. 35 Issue 10, p834 

    It is recognized that the broad-band fluctuations observed in plasmas of thermonuclear devices are the cause of anomalously large energy and particle transport. Strong progress has been achieved on different plasma devices using a heavy ion beam probe (HIBP) diagnostic measuring the plasma...

  • A monitor of chord-averaged plasma density. Petrov, V.; Petrov, A.; Malyshev, A.; Markov, V.; Babarykin, A. // Instruments & Experimental Techniques;Mar2006, Vol. 49 Issue 2, p238 

    A single-channel two-frequency chord-averaged density monitor for measuring the plasma density in tokamaks is described. The operating principle of the monitor is based on measuring the phase shift between two microwave signals at close frequencies transmitted through plasma along one and the...

  • Second stable regime of internal kink modes excited by barely passing energetic ions in tokamak plasmas. He, H. D.; Dong, J. Q.; Fu, G. Y.; Zheng, G. Y.; Sheng, Z. M.; Long, Y. X.; He, Z. X.; Jiang, H. B.; Shen, Y.; Wang, L. F. // Physics of Plasmas;Aug2010, Vol. 17 Issue 8, p082512 

    The internal kink (fishbone) modes, driven by barely passing energetic ions (EIs), are numerically studied with the spatial distribution of the EIs taking into account. It is found that the modes with frequencies comparable to the toroidal precession frequencies are excited by resonant...

  • Lower Hybrid Wave Induced SOL Emissivity Variation at High Density on the Alcator C-Mod Tokamak. Faust, I.; Terry, J. L.; Reinke, M. L.; Meneghini, O.; Shiraiwa, S.; Wallace, G. M.; Parker, R. R.; Schmidt, A. E.; Wilson, J. R. // AIP Conference Proceedings;12/23/2011, Vol. 1406 Issue 1, p231 

    Lower Hybrid Current Drive (LHCD) in the Alcator C-Mod tokamak provides current profile control for the generation of Advanced Tokamak (AT) plasmas. Non-thermal electron bremsstrahlung emission decreases dramatically at ne>1·1020[m-3] for diverted discharges, indicating low current drive...

  • Direct measurement of energetic electron flow in Q-shu University experiment with steady-state spherical tokamak. Ishiguro, Masaki; Hanada, Kazuaki; Liu, Haiqing; Zushi, Hideki; Yoshida, Naoaki; Tokunaga, Tomonori; Nakamura, Kazuo; Fujisawa, Akihide; Idei, Hiroshi; Sakamoto, Mizuki; Hasegawa, Makoto; Tashima, Saya; Takase, Yuichi; Maekawa, Takashi; Kishimoto, Yasuaki; Mitarai, Osamu; Kawasaki, Shoji; Nakashima, Hisatoshi; Higashijima, Aki // Review of Scientific Instruments;Nov2011, Vol. 82 Issue 11, p113509 

    In magnetized plasmas, the presence of a significant number of energetic electrons has been observed but quantitative characteristics of these electrons are proving difficult to investigate. A Langmuir probe offers a means to provide quantitative measurement of these energetic electrons that...

  • Behavior of Small-Scale Density Fluctuations in Discharges with Off-Axis Electron-Cyclotron Resonance Heating in the T-10 Tokamak. Shelukhin, D. A.; Vershkov, V. A.; Razumova, K. A. // Plasma Physics Reports; 

    In experiments on off-axis electron-cyclotron resonance heating in the T-10 tokamak, a steep gradient of the electron temperature was observed to form for a short time at a relative radius of ρ≈0.25 after the heating power was switched off. Small-scale fluctuations of the electron...

  • Plasma density behavior with new graphite limiters in the Hefei Tokamak-7. Asif, M.; Gao, X.; Li, J.; Kuang, G. L.; Wan, B. N.; Jie, Y. X.; Zhao, J. Y.; Zhang, X. D.; Liu, H. Q.; Tong, X. D.; Liu, J.; Xu, Q.; Hu, J. S.; Yang, Y.; Shen, B.; Mao, J. S.; Hu, L. Q.; Wu, Z. W.; Ling, B. L. // Physics of Plasmas;Aug2005, Vol. 12 Issue 8, p082502 

    A new set of actively cooled toroidal double-ring graphite limiters has been developed in the Hefei Tokamak-7 (HT-7) [X. Gao et al., Phys. Plasmas 7, 2933 (2000)] for long pulse operation. The extension of operational region and density behavior with graphite (C) limiters have been studied in...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics