摘要:

The hydrogen plasma produced by a coaxialE × Bgun located in a magnetic mirror system was extensively studied. When the gun was externally shorted (crowbarred) at peak avalanche current, the magnitude of the reverse current due to the angular momentum of the rotating plasma was found to depend on the axial position of the gun with respect to the upstream magnetic mirror. Microwave measurements gave a maximum electron density of 1.7 × 1013cm−3in the presence of neutrals of 1014cm−3with electron decay times of 300 to 400 &mgr;sec in the 1011to 1012per cm3range. Analysis of the optical spectra showed the presence of H, H2, Fe, Fe+, Cr, Cr+, Mn, Mn+, and Mo, and indicated that the electron temperature was approximately 5 eV. Evidence is presented which indicates that internal shorting of the discharge is the result of a low‐resistance path developing along the axial magnetic field lines to the downstream chamber walls. Floating probe measurements revealed that the electric field depended both on current and radial position, and showed little evidence of an anode sheath. Some measurements were also taken with helium and nitrogen as working gases.

ISSN:0031-9171    

DOI:10.1063/1.1762159

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An infinite plasma containing a uniform magnetic field is considered. Self‐consistent solutions were found to two examples concerning the intensification of magnetic field by using magnetohydrodynamic equations with finite conductivity. In the first example, half of the infinite plasma moves perpendicular to the magnetic field and a finite amount of magnetic field is produced in the direction of motion of the plasma. When the velocity of the semi‐infinite plasma is assumed to be independent of time, the magnetic field produced is proportional tot½and it is possible to produce any amount of magnetic field. However, the later situation is not realistic. In the second example, it is assumed that att= 0 an external force alongxaxis acts in the region −a≤z≤aand produces a component of the magnetic field along its direction of motion. The application of this example to the sun shows that large convective cells rising in the presence of the magnetic field of the sun can give rise to a strong magnetic field (∼ 104G) in the direction of the convective motion.

ISSN:0031-9171    

DOI:10.1063/1.1762160

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An anisotropic Maxwellian velocity distribution with loss cones is used to investigate cyclotron wave instabilities occurring in a magnetic mirror configuration. The density of electrons in the loss cones is assumed to be negligible; this implies that the particle velocity distribution function is such thatf0(v⊥,vz) = 0 for |vz| >v⊥(R− 1)½, wherevzis the component of particle velocity along the magnetic field,v⊥ is the component of particle velocity transverse to the magnetic field, andRis the mirror ratio. Linearized Vlasov equations are solved to obtain the dispersion relation for transverse electromagnetic waves propagating along a uniform magnetic field. Numerical solutions of the growth and damping rates of the wave for a mirror ratio of 2.0 show that there is a long‐wavelength instability for a Maxwellian electron distribution with loss cones. The applicability of the analysis to a finite‐length mirror configuration is discussed.

ISSN:0031-9171    

DOI:10.1063/1.1762161

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The inclusion of electron‐neutral collisions in computer simulation calculations is demonstrated. Only one‐dimensional fields are considered in diodes with plane‐parallel symmetry. The method used is to change the velocities of particles in a random manner according to their probabilities of suffering a collision. The method is applied to the hard‐sphere type of collisions between electrons and neutrals. Three examples are shown, and in two of them comparison between analytical and computer simulation results are possible. Reasonably good agreements are obtained. It is demonstrated that the inclusion of electron‐neutral collisions into computer simulation procedures could be used for finding the damping effect of these collisions on the oscillatory behavior of unstable plasma diodes. With this method we can compute the large‐signal, time‐dependent characteristics of diodes at intermediate pressures in which the mean‐free path is comparable to the diode distance.

ISSN:0031-9171    

DOI:10.1063/1.1762162

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Exploratory measurements have been made to evaluate the hot‐film technique for flows of water with high molecular weight additives. Even a minute amount of additives considerably influence the heat transfer characteristics of the hot‐film probe.

ISSN:0031-9171    

DOI:10.1063/1.1762163

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Due to inconsistencies in earlier data for &agr;Tfor Xe&sngbnd;Ne mixtures, this system was reinvestigated. The present results show that one of the earlier sets of data is in error and that the composition dependence of &agr;Tagrees with theoretical expectations.

ISSN:0031-9171    

DOI:10.1063/1.1762164

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

In the context of the higher‐order Chew‐Goldberger‐Low theory an expression for the magnetic moment invariant &mgr;jis obtained correct to first order in the expansion parameter.

ISSN:0031-9171    

DOI:10.1063/1.1762165

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is shown that the general pair correlation function of Balescu and Taylor reduces directly to the correct expression in the case of equilibrium.

ISSN:0031-9171    

DOI:10.1063/1.1762166

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The rate of resistive diffusion is computed using an expansion near the magnetic axis of a hydromagnetic equilibrium under the hypothesis of a steady state. A different limiting case is mentioned for comparison.

ISSN:0031-9171    

DOI:10.1063/1.1762167

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is found that for disturbance at about 0.5 of the thermal speed approximately one self‐collision time is enough for the distribution function to approach Maxwellian, and the time required increases rapidly as the disturbance moves to high velocity.

ISSN:0031-9171    

DOI:10.1063/1.1762168

出版商:AIP    

年代:1967

数据来源: AIP