Response of Plasmas to Tungsten Pellet Injection in Neutral Beam Heated Discharges in Large Helical Device

• OISHI Tetsutarou

  National Institute for Fusion Science, National Institutes of Natural Sciences Department of Fusion Science, SOKENDAI (Graduate University for Advanced Studies)

• MORITA Shigeru

  National Institute for Fusion Science, National Institutes of Natural Sciences Department of Fusion Science, SOKENDAI (Graduate University for Advanced Studies)

• HUANG Xianli

  National Institute for Fusion Science, National Institutes of Natural Sciences

• LIU Yang

  Department of Fusion Science, SOKENDAI (Graduate University for Advanced Studies)

• GOTO Motoshi

  National Institute for Fusion Science, National Institutes of Natural Sciences Department of Fusion Science, SOKENDAI (Graduate University for Advanced Studies)

• the LHD Experiment Group

  National Institute for Fusion Science, National Institutes of Natural Sciences

Abstract

Response of plasmas in Large Helical Device (LHD) to the tungsten pellet injection depends on both the total port-through power of the neutral beam injection (NBI) for heating, P_NBI, and the line-averaged electron density, n_e. The plasma can be sustained in the range of high P_NBI and low n_e while it collapses in the range of low P_NBI and high n_e. When the number of tungsten atoms enclosed in a pellet, N_W, is small, plasma can survive in low P_NBI and high n_e range. Parameter space for plasma sustainment after the pellet injection is limited to lower n_e range in more outward-shifted magnetic configuration. n_e < 4.0 × 10¹³ cm⁻³ and N_W < 1.2 × 10¹⁸ for R_ax = 3.60 m, n_e < 3.0 × 10¹³ cm⁻³ and N_W < 8.7 × 10¹⁶ for R_ax = 3.75 m, and n_e < 2.0 × 10¹³ cm⁻³ and N_W < 3.1 × 10¹⁶ for R_ax = 3.90 m are appropriate parameter ranges for the plasma sustainment. This suggests that robustness against tungsten injection depends on the magnetic configurations.

Journal

• Plasma and Fusion Research

  Plasma and Fusion Research 13 (0), 3402031-3402031, 2018-04-24

  The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

• impurity pellet
• plasma spectroscopy
• magnetically confined fusion
• impurity transport
• tungsten

Details

• CRID: 1390282763013948544
• NII Article ID: 130007396443
• NII Book ID: AA12346675
• DOI: 10.1585/pfr.13.3402031
• ISSN: 18806821
• HANDLE: 10655/00013290
• Web Site: https://nifs-repository.repo.nii.ac.jp/records/11360
• Web Site: https://www.jstage.jst.go.jp/article/pfr/13/0/13_3402031/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • IRDB
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed