PPPL-3977 is available in <a href="PPPL-3977.pdf">pdf</a> format (780 KB).

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<b>Criteria for Second Stability for Ballooning Modes in Stellarators
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<b>Authors:</b> S.R. Hudson and C.C.Hegna
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<b>Date of PPPL Report:</b> July 2004
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<b>Published in:</b> Phys. Plasmas <b>11</b>:9 (September 2004) L53-L56.
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An expression determining how variations in the pressure-gradient and average magnetic shear affect ballooning stability for a stellarator equilibrium is presented. The procedure for determining the marginal stability boundaries, for each field line, depends only on the equilibrium and a single ballooning eigenfunction calculation. This information is sufficient to determine if increasing pressure-gradient is stabilizing or destabilizing and to predict whether the configuration possess a second stable region.




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