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Energetic Particle Experiments in JT-60U and Their Implications for a Fusion Reactor

K. Tobita, Y. Kusama, K. Shinohara, T. Nishitani, H. Kimura, G. J. Kramer, M. Nemoto, T. Kondoh, T. Oikawa, A. Morioka, K. Hamamatsu, S. Wang, S. Takeji, M. Takechi, M. Ishikawa, K. Tani, M. Saigusa, T. Ozeki

Fusion Science and Technology / Volume 42 / Number 2,3 / September 2002 / Pages 315-326

Technical Paper

Energetic particle experiments in JT-60U are summarized, mainly covering ripple loss and Alfvén eigenmodes (AE modes). Significant loss was observed for 85 keV neutral beam injected (NBI) ions and fusion-produced tritons as toroidal field ripple at the plasma surface increased, especially in a reversed shear plasma. Measurement of hot spots on the first wall due to ripple loss confirmed agreement with code predictions, validating the modeling incorporated in an orbit-following Monte Carlo code. A variety of AE modes were destabilized in ion cyclotron range of frequencies (ICRF) minority heating and negative-ion-based NBI (N-NBI) heating. Most of the observed modes are gap modes identified to be toroidicity-induced, ellipticity-induced, and triangularity-induced AE modes. An interesting finding is pulsating modes accompanying frequency sweep, which were destabilized by N-NBI and sometimes induced a beam ion loss of up to 25%. Also presented are energetic particle issues in auxiliary heating with ICRF and N-NBI.

 
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