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Author(s):
S. Murakami, N. Nakajima, S. Okamura, M. Okamoto and U. Gasparino
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Title:
Orbit Effects of Energetic Particles on the Reachable beta-Value and the Radial Electric Field in NBI and ECR Heated Heliotron Plasmas
Date of publication:
Sep. 1996
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Key words:
energetic particle, high beta, radial electric field, NBI heating, ECR heating, heliotron, power deposition, Monte Carlo simulation
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Abstract:
Effects of energetic particles on the plasma heating process and the radial electric field are studied in NBI and ECR heated heliotrons. The NBI heating effficiency is reduced as the magnetic field becomes weak even for tangential injection due to large orbit deviation, which is changed significantly by finite beta effects. It is found that this reduction of the heating efficiency due to beam orbit loss plays an important role to determine the reachable beta-value in the high beta experiments on the Compact Helical System (CHS). It is also found that the radial flux due to tangentially injected NBI beams can enhance the strong negative radial electric field near the plasma periphery in the CHS and the enhancement of radial electric field is larger for high density case which is consistent with experimental results. Effects of energetic electrons on the heating process and the radial electric field in ECR heating are also studied using newly developed Monte Carlo simulation code. The large radial broadening of power deposition profile and radial flux due to the energetic electrons are obtained. This radial flux can enhance the positive radial electric field with siguificant heating power, which can explain the transition phenomena of radial electric field in the CHS experiments.
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