[Table of Contents]

Plasma and Fusion Research

Volume 1, 033 (2006)

Regular Articles


Observation of the Effect of Energetic Ions on Pellet Ablation in the Large Helical Device
Mitsuyasu HOSHINO, Ryuichi SAKAMOTO1), Hiroshi YAMADA1,2), Tokihiko TOKUZAWA1), Kazumichi NARIHARA1), Masaki OSAKABE1), Hisayoshi FUNABA1), Ryuhei KUMAZAWA1), Tetsuo WATARI1) and the LHD Experimental Group1)
Department of Energy Engineering and Science, Nagoya University
1)
National Institute for Fusion Science
2)
The Graduate University for Advanced Studies, SOKENDAI
(Received 10 January 2006 / Accepted 24 April 2006 / Published 23 June 2006)

Abstract

Ablation of a solid hydrogen pellet in hot plasmas was investigated in the Large Helical Device (LHD). The penetration depth of the injected pellets in the experiment was compared to a theoretical model employing ablation due to the heat flux of fast ions as well as thermal electrons. Shallower penetration than that predicted based on the model considering only electrons was observed in LHD plasmas in the presence of highly energetic (up to 180 keV) fast ions due to neutral beam injection (NBI). This discrepancy can be quantified by the contribution of fast ions in terms of the stored energy of fast ions. The ablation model calculation taking into consideration the effect of thermal electrons and fast ions agrees with the experimental results obtained by LHD. Scaling which includes the fast-ion effect on penetration depth in LHD was compared with the wider multi-experiment database (IPADBASE) [L.R. Baylor et al., Nucl. Fusion 37, 445 (1997)].


Keywords

fueling, ablation of solid hydrogen, neutral gas shielding model, fast ions, LHD, IPADBASE

DOI: 10.1585/pfr.1.033


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This paper may be cited as follows:

Mitsuyasu HOSHINO, Ryuichi SAKAMOTO, Hiroshi YAMADA, Tokihiko TOKUZAWA, Kazumichi NARIHARA, Masaki OSAKABE, Hisayoshi FUNABA, Ryuhei KUMAZAWA, Tetsuo WATARI and the LHD Experimental Group, Plasma Fusion Res. 1, 033 (2006).