Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp01np193c633
 Title: Parallel electron force balance and the L-H transition Contributors: Stoltzfus-Dueck, T.U. S. Department of Energy contract number DE-AC02-09CH11466 Keywords: L-H transitionTokamakReynolds stressZonal flows Issue Date: May-2016 Publisher: Princeton Plasma Physics Laboratory, Princeton University Related Publication: Physics of Plasmas, Vol. 23, p. 054505 (May 2016) Abstract: In one popular description of the L-H transition, energy transfer to the mean flows directly depletes turbulence fluctuation energy, resulting in suppression of the turbulence and a corresponding transport bifurcation. However, electron parallel force balance couples nonzonal velocity fluctuations with electron pressure fluctuations on rapid timescales, comparable with the electron transit time. For this reason, energy in the nonzonal velocity stays in a fairly fixed ratio to the free energy in electron density fluctuations, at least for frequency scales much slower than electron transit. In order for direct depletion of the energy in turbulent fluctuations to cause the L-H transition, energy transfer via Reynolds stress must therefore drain enough energy to significantly reduce the sum of the free energy in nonzonal velocities and electron pressure fluctuations. At low k, the electron thermal free energy is much larger than the energy in nonzonal velocities, posing a stark challenge for this model of the L-H transition. URI: http://arks.princeton.edu/ark:/88435/dsp01np193c633 Referenced By: http://dx.doi.org/10.1063/1.4951015 Appears in Collections: NSTX-U

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