摘要:

It is shown that an impurity radiation cooling can give rise to a novel magnetic condensation thermal instability in nonuniform unmagnetized electron plasmas. The resulting enhanced magnetic fluctuations can be responsible for the magnetic turbulence in unmagnetized plasmas.

ISSN:0899-8221    

DOI:10.1063/1.858931

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

An exact solution for strongly nonlinear electrostatic surface waves on a cylindrical boundary of a plasma medium is presented. The effective nonlinear dielectric constant turns out to be dependent upon the geometry as well as the electric field amplitude.

ISSN:0899-8221    

DOI:10.1063/1.858932

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Tokamaks with cross sections elongated in the axial direction are subject to an instability that basically involves an axial displacement of the plasma. This instability can be stabilized by a feedback circuit. This Brief Communication deals with the long‐term development of the plasma after a failure of the feedback circuit during an otherwise normal discharge. The short‐term (linear) development of such a plasma was considered earlier by Yokomizoetal. [Nucl. Fusion23, 1593 (1983)]. During the long‐term development, the plasma makes intimate contact with the surrounding conducting shell (vacuum vessel). The timescale for this development is long compared to the Alfve`n time, so that it is appropriate to consider the plasma in a magnetohydrodynamic (MHD) equlibrium which evolves slowly. This equilibrium (assumed axisymmetric) is unusual in that currents and forces are exchanged between the shell and the plasma. The dynamics of the equilibrium is determined by Ohmic dissipation associated with the plasma currents and the toroidal and poloidal currents of the shell. For a ‘‘typical’’ large tokamak, it is found that dissipation in the shell may dominate. Modeling of such long‐term development may be important because the forces acting on the shell due to the shell currents may be large. It may be important that dissipation in the plasma can be neglected or that it is small in such modeling since the uncertainty of the results, due to uncertainties associated with the plasma, is absent or may be small.

ISSN:0899-8221    

DOI:10.1063/1.858933

出版商:AIP    

年代:1989

数据来源: AIP