摘要:

The propagation and instability characteristics of small signal interfacial waves are examined for charged fluids in planar, cylindrical, and spherical equilibrium. The configurations discussed are electrohydrodynamic versions of the classic fluid mechanical problems of the Rayleigh‐Taylor instability with superposed charged layers, of interfacial capillary oscillations of charged liquid cylinders, and extensions of Rayleigh's and Bohr's analysis of charged spherical drops under surface tension. In these geometries, a liquid which is either electrically perfectly conducting with surface charge or perfectly insulating and polarizable with volume charge is immersed within a uniformly charged perfectly insulating region. Using a general set of relations for perturbation field and flow variables defined for a “prototype” layer, the dispersion characteristics for these two limits are easily derived using interfacial boundary conditions and are compared in each of the geometries. For all cases, the system tends to be stabilized if the charges in each region are of opposite sign.

ISSN:0031-9171    

DOI:10.1063/1.1694721

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The electron temperature of a shock tube magnetohydrodynamic plasma was measured by the line‐reversal method. In order to reduce the influence of self‐reversal in the cool boundary layer on the measurement, the use of nonresonance lines of the potassium seeding was first explored theoretically, then confirmed by experiment. Best suited lines were selected by integrating the radiative transfer equation over both the wavelength and the width of the shock tube assuming a boundary‐layer temperature profile. A lower limit to the population density of the upper level of the selected transition(4p‐6s)was found from the rate equation for this level. The electron temperature distribution along the plasma column was measured using Moutet's double beam version of the line‐reversal method. The measurements show good correspondence between the temporal evolution of the electron temperature in the center of the flow and the generator current. The discrepancy between the measured electron temperature and the gas temperature calculated from the shock Mach number is explained by the occurrence of nonequilibrium ionization.

ISSN:0031-9171    

DOI:10.1063/1.1694722

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A similarity transformation is given, which reduces the partial, nonlinear differential equations describing a compressible, polytropic plasma flow across an azimuthal magnetic field in a duct with plane inclined walls to an ordinary nonlinear differential equation of second order. The latter is solved rigorously in terms of a hyperelliptic integral. The form of the plasma flow fields in pure outflows (diffuser) is discussed analytically in dependence of the Reynolds(R)and Hartmann(H)numbers and the polytropic coefficient(&ggr;)for given duct angles&thgr;0. The realizable Mach numbers are shown to be eigenvalues of the nonlinear boundary‐value problem,M = M(R, H, &ggr;, &thgr;0).

ISSN:0031-9171    

DOI:10.1063/1.1694723

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Assuming thermodynamic equilibrium and using the BBGKY hierarchy, the configuration space and number density distributions of electrons and ions in a plasma bounded by a charged, perfectly conducting surface are derived. Modifying the conventional Debye‐Hu¨ckel approach, the method of images is combined with the use of the Gibbs distribution to obtain new results. It is also shown that the addition of a magnetic field cannot produce any net current if thermodynamic equilibrium is assumed. A drift current is exactly canceled by the current produced by the variation in the number density of particles gyrating about their guiding centers.

ISSN:0031-9171    

DOI:10.1063/1.1694724

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

It is shown that, in addition to the classical(D⊥ ∼ B−2), plateau(D⊥ ∼ B0), and Bohm(D⊥ ∼ B−1)diffusions, there is a new region of diffusion between the classical and the plateau regions where the diffusion increases with increasing the magnetic field. In this region, the lifetime of the convective cells is determined by the ion collisional viscosity and, therefore, this region is important for a plasma with large ion mass.

ISSN:0031-9171    

DOI:10.1063/1.1694725

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The existence of steady‐state solutions to the linearized ion and electron Vlasov equation is demonstrated for longitudinal waves in an initially stable plasma. The evolution of an arbitrary initial perturbation can be described by superposition of these solutions. Some common approximations to the full set of equations can be solved in the same way. In some special cases, relevant, for instance, for single‐endedQmachine experiments, a problem with given boundary conditions can be solved by superposition of normal modes.

ISSN:0031-9171    

DOI:10.1063/1.1694726

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.1694727

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The Green's functions for the linearized ion Vlasov equation with a given boundary value are derived. The propagation properties of ion acoustic waves are calculated by performing convolution integrals over the Green's functions. ForTe/Tiless than about 3 it is concluded that the collective interaction is very weak and that the propagation properties are determined almost completely by freely streaming ions. The wave damping, being due to phase mixing, is determined by the width of the perturbed distribution function rather than by the slope of the undisturbed distribution function at the phase velocity as concluded from normal mode calculations.

ISSN:0031-9171    

DOI:10.1063/1.1694728

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Localized (i.e., Suydam‐type) displacements are considered in the energy principle for arbitrary closed‐line equilibria (constant rational rotational number). The resulting necessary stability condition is more pessimistic than any previously known necessary conditions for closed‐line equilibria, but more optimistic than the low‐shear limit of the corresponding condition for equilibria with shear. A discussion is given of the presently available stability conditions for general toroidal equilibria with or without shear and of their interrelations.

ISSN:0031-9171    

DOI:10.1063/1.1694729

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The rate at which ions are transported from the body to the nonthermal tail of the distribution function during the nonlinear stage of the ion acoustic instability is calculated self‐consistently. The nonlinear stage is characterized by a very small growth rate and a tail whose population increases slowly in time. The calculation is done by conserving the energy and momentum of ions, electrons, and electrostatic fields in the linear and nonlinear regime. These two conservation laws give rise to two equations for growth rate and phase velocity.

ISSN:0031-9171    

DOI:10.1063/1.1694730

出版商:AIP    

年代:1974

数据来源: AIP