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Author: James D Callen
Requested Type: Poster
Submitted: 2016-02-12 16:49:31

Co-authors: C.C. Hegna, M.T. Beidler

Contact Info:
University of Wisconsin
1500 Engineering Drive
Madison, WI   53706-1

Abstract Text:
Recent DIII-D experiments [1,2] have shown that when externally applied resonant magnetic perturbations (RMPs) are large enough to suppress ELMs they abruptly: 1) bifurcate the pedestal plasma profiles, 2) produce tearing-type magnetic responses, 3) increase the toroidal flow velocity; 4) reduce the pedestal top electron density and temperature gradients, and 5) apparently do not produce significant width magnetic islands or stochasticity. These RMP effects are analogous to those predicted by forced magnetic reconnection (FMR) field error theories that use sheared slab [3] or cylindrical [4] magnetic field models. A comprehensive tokamak FMR theory that facilitates exploration of space-time effects and is applicable to the tokamak magnetic field geometry and low collisionality plasmas is being developed. Its key equations govern evolution of the: 1) radial component of a single helically resonant magnetic perturbation including flow-screening effects, 2) parallel plasma vorticity, 3) magnetic island width, and 4) plasma toroidal rotation [5]. These equations use axisymmetric toroidal and local helical magnetic geometries, and kinetic-based [6] generalizations of the slab [3] and cylindrical [4] fluid-based models. They provide criteria for resonant magnetic field penetration, resistive reconnection, island initiation and possible growth, and plasma transport [6] induced by small resonant perturbed fields that can be compared to tokamak experimental results such as those in DIII-D [1,2].
[1] C. Paz-Soldan et al., Phys. Rev. Lett. 114, 105001 (2015).
[2] R. Nazikian et al., Phys. Rev. Lett. 114, 105002 (2015).
[3] T.S. Hahm and R.M. Kulsrud, Phys. Fluids 28, 2412 (1985).
[4] R. Fitzpatrick, Nucl. Fusion 33, 1049 (1993).
[5] J.D. Callen, A.J. Cole and C.C. Hegna, Phys. Plasmas 16, 082504 (2009); Erratum 20 069901 (2013).
[6] J.D. Callen, A.J. Cole and C.C. Hegna, Phys. Plasmas 19, 112505 (2012).
Supported by OFES DoE grants DE-FG02-86ER53218, DE-FG02-92ER54139.

Please place next to M.T. Beidler et al. poster on “Forced Magnetic Reconnection Modeling with NIMROD"