Nonaxisymmetric shaping of tokamaks preserving quasiaxisymmetry

Long-Poe Ku; Boozer, Allen H.
August 2009
Physics of Plasmas;Aug2009, Vol. 16 Issue 8, p082506
Academic Journal
If quasiaxisymmetry is preserved, nonaxisymmetric shaping can be used to design tokamaks that do not require current drive, are resilient to disruptions, and have robust plasma stability without feedback. Suggestions for addressing the critical issues of tokamaks can only be validated when presented with sufficient specificity that validating experiments can be designed. The purpose of this paper is to provide that specificity for nonaxisymmetric shaping. Whether nonaxisymmetric shaping is essential, or just an alternative strategy, to the success of tokamak fusion systems can only be assessed after axisymmetric alternatives are suggested and subjected to a similar study. Sequences of three-field-period quasiaxisymmetric plasmas are studied. These sequences address the questions: (1) What can be achieved at various levels of nonaxisymmetric shaping? (2) What simplifications to the coils can be achieved by going to a larger aspect ratio? (3) What range of shaping can be achieved in a single experimental facility? The sequences of plasmas found in this study provide a set of interesting and potentially important configurations.


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