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Title: Avalanches driven by pressure gradients in a magnetized plasma

ORCiD logo [1];  [1]
  1. Department of Physics, University of California, Los Angeles, California 90095, USA
Publication Date:
Sponsoring Org.:
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 11; Related Information: CHORUS Timestamp: 2017-11-17 16:40:13; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Van Compernolle, B., and Morales, G. J.. Avalanches driven by pressure gradients in a magnetized plasma. United States: N. p., 2017. Web. doi:10.1063/1.5001321.
Van Compernolle, B., & Morales, G. J.. Avalanches driven by pressure gradients in a magnetized plasma. United States. doi:10.1063/1.5001321.
Van Compernolle, B., and Morales, G. J.. 2017. "Avalanches driven by pressure gradients in a magnetized plasma". United States. doi:10.1063/1.5001321.
title = {Avalanches driven by pressure gradients in a magnetized plasma},
author = {Van Compernolle, B. and Morales, G. J.},
abstractNote = {},
doi = {10.1063/1.5001321},
journal = {Physics of Plasmas},
number = 11,
volume = 24,
place = {United States},
year = 2017,
month =

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 7, 2018
Publisher's Accepted Manuscript

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  • Kinetic equations for the electromagnetic drift modes are derived and analyzed for the stability of tokamaks in the local approximation. In the dissipationless, hydrodynamic limit, the fifth-order polynomial dispersion relation previously studied is recovered. The kinetic velocity space integrals in the ion dynamics are shown to modify the five principal modes of oscillation and their polarizations. It is shown that in kinetic stability theory the critical plasma pressure defined in magnetohydrodynamic theory determines a transition from microinstability to macroinstability.
  • A hybrid of hydrodynamics and kinetics is used to study the effect of finite plasma pressure on the pressure-gradient driven toroidal drift modes. The linear drift modes of the system are given by a fifth-order polynomial describing the coupling of the electron-drift, the ion-acoustic, and the shear Alfven oscillations. The characteristic frequencies, growth rates, and polarization of the electromagnetic modes are investigated as functions of the parameters of toroidicity, plasma gradients, and plasma pressure.
  • Ion pressure gradient-driven drift modes are analyzed for their parametric dependence on the shear, the toroidal aspect ratio, and the pressure gradient using the ballooning toroidal mode theory. An approximate formula for the anomalous ion thermal conductivity is derived for the turbulent regime.
  • Collisional modes driven by shear in the plasma flow velocity V{sub {parallel}}, parallel to the magnetic field, are shown to exist over significant scale distances while subject to the constraints imposed by gradients in the transverse velocity V{sub E} {proportional to} E {times} B. These constraints make the modes localized over finite distances around the surfaces where V{sub E} reaches a maximum or a minimum. Composite modes that can be constructed as a sequence or a superposition of these elementary normal modes can be excited in regions where the transverse velocity acquires a plateau type of profile that is assumedmore » to be formed after macroscopic Kelvin-Helmholtz modes associated with the shear of V{sub E} have reached their saturation stage. Thus a significant rate of longitudinal plasma momentum transport in the transverse direction to the magnetic field can be produced. The relevance of this analysis to the fluctuations observed in the auroral F region is discussed.« less
  • Stability in the edge region of reversed-field pinches is analyzed within the context of a two-fluid model. Two major sources of instability are identified: in combination with a parallel electric field, either an electron temperature gradient and/or a density gradient leads to rapid growth (of several to many Ohmic heating rates) over a region of several millimeters around the mode-rational surfaces in the edge region. The basic signature of both instabilities is electrostatic. In the case of the density gradient mode, it relies on the effects of electron compressibility, whereas the temperature gradient mode can be identified as the current-convectivemore » instability by taking the limit of zero density gradient, thermal force, and electron compressibility. The possibility of enhanced particle loss and thermal convection as a nonlinear consequence of the instability is indicated. A criterion for the overlap of the linearly unstable regions in the edge of reversed-field pinches is obtained.« less