摘要:

The two‐dimensional transonic flow of a perfectly conducting, inviscid, compressible fluid past a thin body with aligned magnetic field is studied by developing a small‐perturbation theory in the hodograph plane. It is shown that the equations of motion as well as the conditions for possible shock waves can be reduced to those of ordinary flow by a suitable affine‐transformation. Thus, von Ka´rma´n's transonic similarity law is extended to the present class of magneto‐gas‐dynamic flow. In this extension, super‐Alfve´nic flows (flow speed larger than Alfve´n wave speed) are found to be similar to the corresponding ordinary flow, while sub‐Alfve´nic flows are related to the ordinary flow with reversed flow direction. The flow over a half‐wedge at Mach number 1 is considered in detail.

ISSN:0031-9171    

DOI:10.1063/1.1706701

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The entry problem for an annular channel configuration which has the Globe profile for its fully developed condition is solved numerically for various values of the pertinent parameters describing the flow. The nonlinearities present in the momentum and energy equations are utilized in the solution of the problem by placing the equations in a finite difference form. For a large accelerating electric field the velocity profile was found to reverse itself in an area near the outer wall of the channel. Velocity, temperature, and pressure curves are presented from the results of computational work.

ISSN:0031-9171    

DOI:10.1063/1.1706702

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A slightly ionized gas was formed in the wake of a detonation wave in a shock tube by seeding with a potassium salt. Wire electrodes were placed with axes normal to the shock‐tube axis and separated by a variable distance along the tube axis. The heating of each electrode was measured by determining the rate of change of electrical resistance of the electrode. Electrode heating in excess of that due to aerodynamic heat transfer was only observable in the range of 102to 103A/cm2and was found to be proportional to the current. The excess heating rate divided by the total current was measured to be 4.9 V for the anode and 3.2 V for the cathode. By varying the spacing of the electrodes, it was found that the gas resistance could be accounted for by the geometric effects alone in combination with the gas conductivity as measured by Basu for this mixture.

ISSN:0031-9171    

DOI:10.1063/1.1706703

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Single‐fringe interferograms are presented of 4‐mil Cu wires exploded at 20 kV into argon at ambient pressures of 1/8, 1/16, and 1/32 atm. Features discernible include a compressive‐head shock wave, arc plasma, a weak plasma wave and the expanding metal wire. On the basis of certain plausible assumptions it is seen that the arc plasma has a temperature of about 2.5 eV; but its leading edge, a region not in thermal equilibrium, has electron temperatures ∼ 102eV and is the boundary of an electron‐driven shock wave.

ISSN:0031-9171    

DOI:10.1063/1.1706704

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

This paper is concerned with the theoretical solution of electromagnetic wave propagation through a nonuniform plasma sheath bounded by a plane infinite conductor. The governing differential equation yields a set of pseudo wave functions upon which all subsequent analysis is based. An exact solution is obtained for normal incidence and an excellent approximate solution for oblique incidence in the particular case of an assumed exponentially varying conductivity distribution. The procedures developed are applied to two practical cases, namely a penetration problem and a radiation problem. After establishing the proper orders of magnitude of the involved parameters from practical considerations, appropriate numerical data are obtained.

ISSN:0031-9171    

DOI:10.1063/1.1706705

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Kinetic models for multicomponent gases are given. It is shown that some of the most important features of the Boltzmann equation are retained in spite of the simplicity of the model equations. An iteration procedure on the model equation is carried out and is identified with the Chapman‐Enskog procedure. Linear and nonlinear formal procedures for developing the models and their extensions are also given.

ISSN:0031-9171    

DOI:10.1063/1.1706706

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A kinetic model, which is based on an approximation to the complete Boltzmann equation, is developed for the purpose of solving flow problems in the high velocity ratio, large Knudsen number regime. The approximation consists of substituting appropriate &dgr; functions for certain portions of the distribution function wherever they appear in a collision integral. The Boltzmann equation reduces to a first‐order linear inhomogeneous partial differential equation in this approximation, and the detailed intermolecular differential scattering cross section appears explicitly in the inhomogeneous term. The model is applied to the solution of the hypersonic Couette flow of a rarefied hard‐sphere gas.

ISSN:0031-9171    

DOI:10.1063/1.1706707

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Classical scattering by repulsive potentials of the formV = Br−nexp (−r/a) is analyzed in terms of two energy‐dependent parameters, the distance of closest approach in head‐on collisionc, and a slope parameter &ggr; = −(dlnV/dlnr)r=c. Use of these brings out important relationships among values of cross sections for various potentials which are in the literature and also facilitates the derivation of certain asymptotic analytic relations, the most interesting applying when &ggr; is large, and others when &ggr; is near unity. For large &ggr;, the differential cross section &sgr;(&thgr;) is given by 4&sgr;(&thgr;)/c2= 1 +Q1/&ggr; +Q2/&ggr;2, whereQ1is a simple function of &thgr; only, whileQ2is a more complicated function which depends also onn/&ggr;. This asymptotic expression for &sgr;(&thgr;) and transport cross sections &sgr;lcalculated from it are compared with some of the available data. For the exponential potential, the asymptotic analytic behavior of collision integralsI(l, s)for large values of &agr; = ln (B/kT) is determined and compared with numerical results of Monchick. For the exponentially screened Coulomb potential, a simple expression describing the dependence of &sgr;1/&pgr;c2on &ggr; is selected and used in treating the energy loss of a fast heavy atom being stopped by elastic collisions in a gas of light atoms. This discussion makes clearer the basis and scope of the Bohr‐Nielsen range‐energy equation.

ISSN:0031-9171    

DOI:10.1063/1.1706708

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The Vlasov equation is considered without magnetic fields, linearized about a state with no electric fields or space and time variation. Integral representations for the Green's functions are presented for systems of one, two, and three dimensions. For the one‐dimensional stable case, two asymptotic expansions of the electric field for large time are presented. Similar expansions are given for a specific example of a one‐dimensional unstable plasma. In two and three dimensions, asymptotic expansions are exhibited for arbitrary plasmas having cylindrical or spherical symmetry.

ISSN:0031-9171    

DOI:10.1063/1.1706709

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The problem of the oscillations of a ``collisionless'' electron plasma confined by specularly reflecting walls is solved. The device is to replace the boundary conditions by an equivalent, infinite, spatially periodic plasma which has a certain symmetry in velocity space. The spectrum of eigenfrequencies can be determined from a consideration of the equivalent unbounded situation.

ISSN:0031-9171    

DOI:10.1063/1.1706710

出版商:AIP    

年代:1962

数据来源: AIP