摘要:

A low‐&bgr; plasma can stream across a “slab” of magnetic field provided the spatial extentLof the field along the streaming direction is small compared with the geometric mean cyclotron radius and provided the magnetic field is not too strong(&ohgr;ce≲ &ohgr;pc). The behavior of the plasma which emerges from the magnetic field region is discussed here. On a scale large compared withL, the effect of the magnetic field is simply to impart an impulsive transverse velocity to the electrons of the streaming plasma. If this velocity exceeds the stability limit for the two‐stream instability, long‐wavelength, longitudinal thermal fluctuations should grow to such an amplitude that the resulting weak turbulence reduces the transverse velocity to zero, the associated kinetic energy being converted to electron thermal energy. A solution to this problem within the quasilinear approximation for a “collisionless” plasma is given here, together with numerical calculations of the spatial decay of the current and the associated electron heating. As expected, the length of the turbulent transition region, in which the directed transverse energy is thermalized, is an increasing function of the initial plasma density, but a decreasing function of the initial electron temperature and transverse velocity. A small charge separation(ni− ni≲ 10−4ne)provides an electric field just sufficient to balance the pressure gradient,n dT / dx.

ISSN:0031-9171    

DOI:10.1063/1.1691883

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The problem of a particle trapped in a time‐dependent meridional magnetic mirror field and at the same time subjected to a time‐dependent perpendicular electric field(E·B = 0)is considered. Bounce‐averaged guiding‐center theory is used to derive expressions for the drift velocity conponents. These drift expressions depend in a straightforward fashion on the structures of the magnetic and electric fields and on the particle charge, kinetic energy, longitudinal invariant, and bounce period. In the special case of a static magnetic field, no electric field, andJ = 0particles, the drift equations are integrated and the bounce‐averaged guiding‐center trajectory obtained.

ISSN:0031-9171    

DOI:10.1063/1.1691884

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

An evaluation has been made of the net ionization frequencies of air inferred from breakdown measurements. This has been accomplished by comparison of such data with the corresponding values obtained from numerical solutions of the Boltzmann equation. Good agreement is found at high pressures, but the comparison deteriorates with decreasing pressure. This trend is attributed to the use of the effective field concept and the absence of nonuniform field corrections in the processing of the experimental data. Calculations are presented that show that breakdown fields calculated with data obtained from solutions of the Boltzmann equation and combined with an appropriate nonuniform field analysis are in good agreement with experimentally measured breakdown fields. It is concluded that the latter approach provides a more rational and accurate method for predicting high‐frequency breakdown than previously available methods.

ISSN:0031-9171    

DOI:10.1063/1.1691885

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The use of an advected white noise base for a truncated expansion is shown to provide an approximation for turbulence which has the inviscid equipartition solution and is invariant to random Galilean transformations.

ISSN:0031-9171    

DOI:10.1063/1.1691886

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A new approximation method as applied to closed streamline flow in a rectangular cavity is described. The particular boundary condition of constant shear stress over the open end of the cavity is examined in detail.

ISSN:0031-9171    

DOI:10.1063/1.1691887

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The results show that the unsymmetrical flow is more stable than the symmetrical flow. An interesting feature of the unsymmetrical flow is the existence of two critical points in the neutral stability curve.

ISSN:0031-9171    

DOI:10.1063/1.1691888

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

An extension of the two‐fluid model to the problem of plane stationary shock waves in binary mixtures of monatomic inert gases is made. No overshoot exists in the velocity profiles; however, there is an overshoot in the temperature profile.

ISSN:0031-9171    

DOI:10.1063/1.1691889

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The form of the inelastic transport cross sections is developed from the macroscopic transport equations. The diffusion cross sections for the Lyman &agr; transitions in hydrogen are discussed.

ISSN:0031-9171    

DOI:10.1063/1.1691890

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Double‐adiabatic hydromagnetic fluid equations for electrons and ions are given that reduce to the Chew‐Goldberger‐Low equations or adiabatic, nonlinear ion‐acoustic equations in special cases.

ISSN:0031-9171    

DOI:10.1063/1.1691891

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A new form is derived for the plasma kinetic equation in which an operator replaces the distribuion function. Transport coefficients can be obtained by a method similar to that of Chapman and Enskog and, under certain conditions, an exact solution can be found.

ISSN:0031-9171    

DOI:10.1063/1.1691892

出版商:AIP    

年代:1968

数据来源: AIP