(EX/P3-6) Confinement of High Energy and High Temperature Ions in the MST Reversed Field Pinch

G. Fiksel1), A.F. Almagri1), J.K. Anderson1), A.D. Beklemishev2), B.E. Chapman1), D. Craig1), V.I. Davydenko2), D.J. Den Hartog1), D. Ennis1), S. Gangadhara1), B. Hudson1), A. Kuritsyn1), A.A. Ivanov2), R.M. Magee1), V.V. Mirnov1), R. O'Connell1), S.C. Prager1), J.S. Sarff1), V. Svidzinski1), Yu.A. Tsidulko2)
1) University of Wisconsin-Madison, Madison, Wisconsin, and the Center for Magnetic Self- Organization in Laboratory and Astrophysical Plasmas, USA
2) Budker Institute of Nuclear Physics, Novosibirsk, Russia

Abstract.  Confinement of both high energy and high temperature ions has been investigated in the Madison Symmetric Torus (MST) Reversed Field Pinch (RFP), both in standard plasmas with magnetic stochasticity, and improved confinement plasmas in which stochasticity is reduced. We find that (1) energetic ions (produced by neutral beam injection) are very well-confined in the standard RFP plasma despite the presence of significant stochasticity. This is understood from theory and simulation, and has positive implications for feasibility of neutral beam injection and alpha-particle confinement; (2) when magnetic stochasticity is reduced the thermal ion confinement is substantially increased as well. This is evidenced from direct observations of long lasting periods of sustained high ion temperature as well as from estimation of ion thermal diffusivity.

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