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Author(s):
K. Nagasaki and K. Itoh
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Title:
Decay Process of a Magnetic Island by Forced Reconnection
Date of publication:
Mar. 1991
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Key words:
magnetic island, forced reconnection, decay process
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Abstract:
Time evolution of a magnetic island by forced reconnection, especially the decay process is analyzed. A simple slab model is used and the magnetic island is considered to have a single helicity. The plasma is assumed to be incompressible. The evolution time is affected by the presence of an original magnetic island. In the decay process, a current flows along the separatrix of the magnetic island, and the current layer Width depends on the magnetic island width, when the island is relatively wide compared to the current Iayer. In the presence of a magnetic island, even if the magnetic Reynolds number S increases, the current layer does not become narrower. This leads to the slow evolution of the magnetic island. It is found that the time scale S^1tau_A is required to reach the last equilibrium regardless of the nonlinear terms. This is slower than that of the growth process, S^(3/5) tau_A..
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