PPPL-3904 is available in <a href="PPPL-3904.pdf">pdf</a> format (2.8 MB).

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<b>Destruction of Invariant Surfaces and Magnetic Coordinates for Perturbed Magnetic Fields </b>
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<b>Author:</b> S.R. Hudson
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<b>Date of PPPL Report:</b> November 2003
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<b>Published in:</b> Physics of Plasmas <b>11</b>:2 (February 2004) 677-685</p>

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Straight-field-line coordinates are constructed for nearly integrable magnetic fields. The coordinates are based on the robust, noble-irrational rotational-transform surfaces, whose existence is determined by an application of Greene's residue criterion. A simple method to locate these surfaces is described. Sequences of surfaces with rotational-transform converging to low order rationals maximize the region of straight-field-line coordinates.






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