摘要:

Recent work by Fox and Uhlenbeck, in which random fluxes were incorporated into the dissipative equations of hydrodynamics for a pure fluid, is extended to binary fluid mixtures.

ISSN:0031-9171    

DOI:10.1063/1.1693545

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Free jets, produced by issuingCO2gas from a supersonic nozzle into high vacuum, have been investigated experimentally by measuring densities and temperatures of the gas. Gas densities are measured using electron beam absorption and luminescence methods. Rotational temperatures are measured, after a theoretical model is developed, by using an unresolved band system of theCO2spectrum. The results indicate that condensation must take place inside the nozzle. Outside the nozzle, the expanding gas gradually leaves the saturation line. At a pressure of about 0.3 Torr the condensation is frozen, and beyond this point the gas essentially follows an isentropic expansion line.

ISSN:0031-9171    

DOI:10.1063/1.1693546

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The effect of thermal radiation on the propagation of small disturbances generated by the harmonic oscillation of a planar wall, either in position or temperature or both, is considered. By separation of variables, it is shown that the governing linearized equations can be reduced to a homogeneous integral equation that admits both regular and singular solutions to form a complete set; thus, the problem can be solved by the application of singular eigenfunction expansions analogous to those used in neutron‐transport theory. An exact closed form solution is obtained for disturbed quantities in the flow and radiation fields. The exact solution shows that the disturbances consist of a damped continuum mode with infinite wave speed in addition to two discrete modes with finite wave speed. One of the discrete modes represents the “modified classical” wave whereas the other discrete mode plus the continuum mode corresponds to the radiation‐induced wave. For sufficiently small Bouguer numbers, the discrete mode of the radiation‐induced wave disappears. The newly found continuum mode damps faster than the discrete mode. Consequently, only the discrete modes persist away from the boundary. The differential approximation is found to predict the modified classical wave accurately but predicts the radiation‐induced wave only approximately. The implications as well as the accuracy of the differential approximation are discussed and compared.

ISSN:0031-9171    

DOI:10.1063/1.1693547

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Flow of rarefied gas over an infinite plane wall on the basis of a relaxation model of the Boltzmann equation is considered. The solution is obtained in the form: Hilbert solution and boundary layer term which is appreciable only in a thin layer (with thickness of order of the mean free path) adjacent to the boundary. The Hilbert part dominates in the region away from the boundary. Using the result the asymptotic behavior (for small mean free path) of plane compressible Couette flow is investigated.

ISSN:0031-9171    

DOI:10.1063/1.1693548

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The effect of temperature nonuniformity on the voltage‐current characteristic of the positive column of a gas discharge is studied theoretically. The coupled electron diffusion and neutral temperature equations are solved by perturbation and numerically. It is found that at currents corresponding to the abnormal glow and higher, the voltage drop of the positive column decreases with increasing current, but this result is quite sensitive to the experimental data. Numerical results are obtained for anH2discharge.

ISSN:0031-9171    

DOI:10.1063/1.1693549

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The rotation of a glow discharge in the homopolar geometry has been studied experimentally. In helium the motion of the discharge is independent of the current level and is attributed to ion drift with the neutrals stationary. In argon at low currents the rotational speed is proportional to the current and the discharge acts like a magnetohydrodynamic pump. At higher pressure in argon the discharge contracts and the rotational speed increases by nearly an order of magnitude.

ISSN:0031-9171    

DOI:10.1063/1.1693550

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Measurements and related analyses of the electron temperature and electron number density in an atmospheric pressure laminar thermal boundary layer adjacent to a cooled wall are described. The analyses proceed from consideration of the coupled electron continuity and electron energy equations with boundary conditions appropriate to NaK seeded argon. It is shown that the theoretical results can be interpreted in terms of three characteristic lengths:&dgr;, the thermal boundary layer thickness,lE, the characteristic length for electron energy exchange, andlI, the characteristic length for ionization. Electron temperature profiles were measured experimentally in the boundary layer described above using a spectroscopic technique, and electron number density profiles were measured using a small traversing probe developed by the authors. The experimental results, obtained for various values of the lengthslEandlI, were found to be in good agreement with the theory.

ISSN:0031-9171    

DOI:10.1063/1.1693551

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The combined nonlinear and collisional effects on the Landau damping of longitudinal electron oscillations are studied using the Lorentz gas model to represent electron‐neutral and electron‐ion interactions. Three types of interactions are considered: hard‐sphere collisions, inverse fifth‐power interactions, and inverse square interactions. A perturbation analysis of the nonlinear kinetic equation is carried out following Montgomery's expansion technique. For hard‐sphere collisions, the collisional damping and the nonlinear change in Landau damping are determined analytically. For inverse fifth‐power interactions and inverse square interactions, the same results are obtained numerically by expanding the distribution function in Legendre polynomials to sufficiently high order to adequately represent its variations in the resonance region.

ISSN:0031-9171    

DOI:10.1063/1.1693552

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The change in the electron distribution function due to a damped electron plasma wave is observed by means of an electron energy analyzer. The results show that the number of particles with velocities greater than that of the wave phase velocity is increased and that the number of particles with velocities less than the wave decreases. The distance between the antenna and analyzer is varied to show the increase in the deformation of the velocity distribution due to wave‐particle interaction through space. For sufficiently high wave power and large separation a plateau is formed in the vicinity of the wave phase velocity.

ISSN:0031-9171    

DOI:10.1063/1.1693553

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The statistics of charged particle dynamics in turbulent plasmas have been studied in a numerical experiment which models a turbulent plasma as a system of uncorrelated plasma waves. The ensemble averaged distribution function roughly “diffuses” in velocity space in both weak and strong field regimes. The experimental data are consistent with Dupree's prediction of a diffusion coefficient having a broadened wave‐particle resonance and scaling quadratically in the electric field strength for weak fields, and proportional toE3/2for stronger fields.

ISSN:0031-9171    

DOI:10.1063/1.1693554

出版商:AIP    

年代:1971

数据来源: AIP