X-ray Measurements during Plasma Current Start-up Experiments using the Lower Hybrid Wave on the TST-2 Spherical Tokamak

Access this Article

Search this Article

Author(s)

Abstract

Non-inductive plasma current start-up experiments using RF power in the lower hybrid frequency range is being conducted on the TST-2 spherical tokamak. Plasma currents of up to 15 kA have been achieved. The effect of direct current drive can be seen by comparing the cases with co-drive and counter-drive. X-rays in various energy ranges were measured to investigate the interaction between the wave and the electrons. Soft X-ray (SX) measurements revealed that the perpendicular SX emission increased significantly as the plasma current increased, and that the tangential SX emission in the direction of RF drive was enhanced more strongly in the co-drive case compared to the counter-drive case. These observations imply that the fast electrons accelerated by the lower hybrid wave contribute to the plasma current. However, RF amplitude modulation experiments showed that the confinement time of these fast electrons are very short (less than 0.05 ms), much shorter than the collisional slowing down time. Hard X-ray spectral measurements showed that the radiation temperature of fast electrons in the co-direction for current drive was higher than that in the counter-direction. These observations are consistent with the existence of RF-driven fast electrons.

Journal

  • IEEJ Transactions on Fundamentals and Materials

    IEEJ Transactions on Fundamentals and Materials 132(7), 485-489, 2012-07-01

    The Institute of Electrical Engineers of Japan

References:  9

Codes

  • NII Article ID (NAID)
    10030777765
  • NII NACSIS-CAT ID (NCID)
    AN10136312
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    03854205
  • NDL Article ID
    023886073
  • NDL Call No.
    Z16-793
  • Data Source
    CJP  NDL  J-STAGE 
Page Top