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Author(s):
K. Akaishi, M. Nakasuga, H. Suzuki, M.Iima, N. Suzuki, A. Komori, O. Motojima and Vacuum Engineering Group
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Title:
Simulation by a Diffusion Model for the Variation of Hydrogen Pressure with Time between
Hydrogen Discharge Shots in LHD
Date of publication:
Feb. 2001
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Key words:
H trapping and desorption, diffusion, recombination, stainless steel Wall, LHD
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Abstract:
When hydrogen gas discharge is carried out in a magnetic fusion experimental device, hydrogen is implanted into the first wall during discharge but is in turn released from the wall in the pause period of discharge shot. To express the hydrogen desorption rate from the wall as a function of time, a diffusion model is presented, in which the transport of trapped hydrogen in the wall is treated by the one dimensional diffusion equation. It is discussed that when the deposition profile of implanted hydrogen in the wall is given as a function of position, the diffusion equation can be solved analytically. The hydrogen desorption rate is numerically calculated using the analytical solution, then it is shown that the calculated desorption rate well explains the experimental hydrogen desorption rate which has been observed as a function of time after hydrogen discharge shot in LHD.
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