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Author(s):
W.X. Wang, M. Okamoto, N. Nakajima, S Murakami and N. Ohyabu
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Title:
Cooling Effect of Secondary Electrons in the High Temperature Divertor Operation
Date of publication:
Feb. 1997
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Key words:
high temperature divertor operation, secondary electron emission, sheath, Monte Carlo simulation
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Abstract:
The scrape-off layer (SOL) plasma is studied over a wide range of Coulomb collisionality via particle Monte Carlo simulation with focus on the cooling effect of secondary electrons in the high temperature divertor operation. Electron distribution function in collisionless regime shows a large departure from Maxwellian. In the presence of strong secondary electron emission the electron sheath energy trans-mission factor in collisionless regime is found to be significantly smaller than that of collisional regime. which indicates a higher temperature obtainable in collision-less SOL plasma. In both collisional and collisionless SOL plasma, the change in the conductive energy flux from the core region into the SOL has little influence on the normalized potential drop and electron energy transmission factor, while the electron temperature is raised as the conductive energy flux increases.
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