摘要:

The Boltzmann equation is used to derive the expression for the current in ionized gases at low density in an axially symmetric nonuniform field. The gas is assumed to be in a steady state and collisionless. Using this method, the usual expression for the total drift current is obtained without the necessity of using first‐order orbit theory. When the integration is made over the whole region of charged particles, the diamagnetic terms clearly will not contribute to the total current.

ISSN:0031-9171    

DOI:10.1063/1.1706820

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Sturrock's variational principle seems particularly well suited to the study of small‐amplitude disturbances of plasma systems and is formulated in a sufficiently general manner so as to be applicable to relativistic as well as nonrelativistic multistream problems. The use of this variational principle is shown to be effective (in conjunction with the trial‐function method) in approximating dispersion relations. To this end the variational procedure is applied to two simple plasma problems which admit of exact solution. It is found that a first‐order error in the trial functions leads to only a second‐order error in the dispersion relation—a behavior typical of variational procedures and which renders them so useful.

ISSN:0031-9171    

DOI:10.1063/1.1706821

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The rigorous expression for the classical high‐frequency conductivity of a fully ionized plasma was obtained earlier through a joint solution, in the plasma limit, of the first two members of the B‐B‐G‐K‐Y hierarchy when both are able to change on the same time scale. [C. Oberman, A. Ron, and J. Dawson, Phys. Fluids5, 1514 (1962)]. That treatment is now extended to include the presence of a uniform magnetic field. Through the use of a Fourier‐Bessel transformation, the equation for the pair correlation function is rendered formally identical to that of the no magnetic field case.

ISSN:0031-9171    

DOI:10.1063/1.1706822

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The motion of an ideal collisionless plasma subject to periodic boundary conditions, with velocity distribution given initially, is studied. The minimum value which the kinetic energy can subsequently attain is determined, on the assumption that the system is subject only to the constraint that phase‐space volume is conserved.

ISSN:0031-9171    

DOI:10.1063/1.1706823

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Electrons are injected axially from an external source into a cusp field. For the particles to be transmitted through the cusp they must be injected inside a ``loss disk'' of radius &rgr;critical= (mv)/(qB0). At larger values of injection radius the depth of penetration beyond the median plane is measured and is in agreement with the maximum penetration depth predicted by the theory. The question of trapping is investigated and no long time confinement is obtained. The maximum number of reflections observed inside the cusp region is five.

ISSN:0031-9171    

DOI:10.1063/1.1706824

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Five plasma configurations were studied in a fast‐programmed toroidal discharge device where magnetic field errors were minimized. The effects of the programming on the plasma were examined with magnetic probes. a Kerr cell camera, and a monochromator. Without programming, the plasma developed a well‐defined kink which corresponded to the worst mode of the instability predicted by hydromagnetic theory. By programming, the plasma lasted for 10 to 15 &mgr;sec at ion temperatures up to 130 eV and with densities up to 3 × 1016cm−3.

ISSN:0031-9171    

DOI:10.1063/1.1706825

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The coefficients of friction and dispersion that appear in the Fokker‐Planck equation describing the thermalization of a test ion in a plasma are approximated. The approximation is valid when the speed of the test ion is less than the average speed of the plasma electrons, but large enough that the plasma electrons interact more strongly with the test ion than do the plasma ions. The resulting Fokker‐Planck equation is solved to obtain an exact analytic expression for the time‐dependent energy distribution function of the test ion. This distribution function is used to examine in detail the nature of the approach to equilibrium.

ISSN:0031-9171    

DOI:10.1063/1.1706826

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An experimental investigation of the containment time of plasma in a theta pinch is described. Observations of changes in the plasma diamagnetism have been made, analysis of which leads to a determination of the field trapping conditions in the plasma and of the variations in line density of the plasma which take place during a discharge. The results show that in parallel field discharges the containment time of the plasma depends on the flux trapped within the plasma, in agreement with theoretical predictions. In particular, the containment time increases as the flux approaches zero. In reversed field discharges the plasma containment is limited by an axial contraction instability, which is slower the lower the amount of reversed trapped flux. At very low values of this flux, the plasma appears to stay contained and stable in a closed reversed field configuration for the period of observation (6 &mgr;sec).

ISSN:0031-9171    

DOI:10.1063/1.1706827

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A hexapole magnetic field has been superimposed on the fast magnetic mirror compression field of the Scylla III &thgr; pinch in an attempt to stabilize an observed plasma instability. The instability is of the flute type with a superimposed rotation. The effect of the hexapole field on the plasma stability was studied with streak camera photography and through observation of the neutron emissions. Under certain conditions the hexapole ``stabilizing'' field has an observable effect on the instability. Its main effect is to symmetrize the rotation about the axis of the compression coil and to produce a delay in the onset of the instability. There is at most a small effect tending to symmetrize the time distribution of neutron emission and to increase the neutron yield.An ionized deuterium plasma is produced by a fast, low energy capacitor bank coupled directly to the single‐turn compression coil of the Scylla III device. The ``afterglow'' of this preionization discharge, uniformly permeated by a magnetic bias fieldB0, forms the initial condition for the application of the main magnetic compression field. The effect of the main compression field on the preionized plasma depends strongly on theB0which exists in the plasma.

ISSN:0031-9171    

DOI:10.1063/1.1706828

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.1706829

出版商:AIP    

年代:1963

数据来源: AIP