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approvedabstract_2017_sherwood.pdf2017-03-15 13:09:29W. Lee

Abstracts

Author: W. W. Lee
Requested Type: Pre-Selected Invited
Submitted: 2017-03-15 13:01:25

Co-authors: R. B. White, S. R. HUdson

Contact Info:
Princeton Plasma Physics Laboratory
1 Stellarator Road
Princeton, NJ   08543
USA

Abstract Text:
We will present a novel mechanism for producing the equilibrium potential well near the edge of a tokamak [1]. Briefly, because of the difference in gyroradii between electrons and ions, an equilibrium electrostatic potential is generated in the presence of spatial inhomogeneity of the background plasma due to [2],

{n_i |_{particle}over n_{i} } =
1 + {1 over 2} rho_i^2 {1 over p_i} nabla_perp^2 p_i,

which, in turn, produces a well associated with the radial electric field, Er, as observed at the edge of many tokamak experiments. We will show that this theoretically predicted Er field, which can be regarded as producing a long radial wave length zonal flow, actually agrees well with recent measurements on JET [3], NSTX [4], and C-MOD [5]. The relationship between the equilibrium pressure balance due to the Finite Larmor Radius effects used in the study [1, 2],

{bf J}_perp approx {c over B}hat{bf b} times (nabla p_i) left [1- {1 over 4}rho_i^2 {nabla^2_perp p_i over p_i} right ],

and the associated MHD equilibria will also be explored.

[1] W. W. Lee and R. B. White, “Equilibrium Potential Well due to FLR effects at the Tokamak Edge,” Phys, Plasmas, to appear (2017).
[2] W. W. Lee, Phys. Plasmas 23, 070705 (2016).
[3] J. C. Hildesheim, E. Delabie, H. Meyer et al., Phys. Rev. Lett. 116, 065002 (2016).
[4] A. Diallo, J. Canik, T. Goerler et al., Nucl. Fusion 53, 1 (2013).
[5] C. Theiler, R, M. Churchill, B. Lipschultz et al., Nucl. Fusion 54, 083017 (2014).

Comments:
Physics of Plasma Edge and Divertor Region