摘要:

The theoretical expressions for the second virial coefficient,B(T), are derived for the (18–6‐3) Stockmayer potential&PHgr;(r)=4&egr;&sgr;r18−&sgr;r6−&mgr;2r3g(&thgr;1,&thgr;2,&Jgr;),whereg(&thgr;1, &thgr;2, &phgr;) = 2 cos &thgr;1cos &thgr;2− sin &thgr;1sin &thgr;2cos &phgr;, and also according to the (28–7‐3) potential. Tables of the reduced virial coefficient are given as a function of the reduced temperature for the (18–6‐3) potential, and experimentalB(T) data are interpreted for a number of gases. The potential parameters are reasonable and reproduce theB(T) data within the limits of experimental errors. The point dipole polarizable model is also considered.

ISSN:0031-9171    

DOI:10.1063/1.1706508

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An expression for the energy exchange between two Maxwellian gases at different temperatures is derived. The resultant formula contains an integral in which the scattering cross section for momentum transfer appears. If the cross section for hard‐sphere collisions is used, the expression reduces to an expression obtained by Cravath for this case. If the cross section for screened Coulomb interactions is used, the results agree with results for the same case obtained by Spitzer and others.

ISSN:0031-9171    

DOI:10.1063/1.1706509

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A three‐fluid theory (using Maxwell's equations together with a set of coupled hydrodynamic equations for an interacting mixture of electrons, ions, and neutral molecules) is used to examine small‐amplitude oscillations in an infinite, homogeneous, partly ionized gas with a uniform external magnetic field. Dispersion relations are obtained when the uniform magnetic field is either parallel or perpendicular to the direction of wave propagation, and the results are interpreted (in the case of negligible collisional damping) by analyzing plots of phase velocity versus frequency. Comparison is made with the simpler one‐fluid theories (the magneto‐ionic theory, magnetohydrodynamics, and acoustics), as well as with the two‐fluid theory for a fully ionized gas. Collisional damping effects are included in all the dispersion relations and are described in detail for the magneto‐ionic and magnetohydrodynamic limits.

ISSN:0031-9171    

DOI:10.1063/1.1706510

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The damping of transverse waves, propagating parallel to an external magnetic field, through a low‐density plasma is studied. It is found that there is a limitation on the total amount of energy which may be absorbed in a unit volume of the gas. This saturation phenomenon is predicted on the basis of a particular nonlinear relativistic effect. The total amount of energy absorbed is found to be proportional to the two‐thirds power of the incident radiation energy flux for a low flux, and proportional to the one‐third power for a high flux.

ISSN:0031-9171    

DOI:10.1063/1.1706511

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Periodic plane waves are considered in a plasma pervaded by a uniform magnetic field. The appropriate linearized Boltzmann equations for the distribution functions of the electrons and of each type of ion are solved exactly. Collisions are taken into account by the inclusion of a simplified collision term. The solutions are used to compute the electric current, from which the conductivity tensor of each ionic species is found. The total conductivity is then used in Maxwell's equations to determine the electromagnetic field, and this leads to the dispersion equation for plane waves. This equation is solved in various parameter ranges for the case of longitudinal waves when the conductivity of only one species is taken into account. The solutions of Landau, Gordeyev, Gross, Bernstein, and others are recovered when the collision frequency vanishes. In addition, various power series and asymptotic expansions for the conductivity tensor are given, and it is shown to reduce to that of the magneto‐ionic theory under suitable conditions. The Appendix contains a systematic study of a function which plays a central role in the theory.

ISSN:0031-9171    

DOI:10.1063/1.1706512

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Properties of growing waves are investigated in a uniform plasma with a doubly humped velocity distribution by studying the character of the boundary curves between growing waves and damped waves. The specific family of distribution functions mainly investigated is one which is composed of a Maxwellian main part plus a small gentle bump (also Maxwellian) on its tail. When a parameter describing the shape of the distribution (the relative strength of the small bump, the separation between the two peaks, etc.) is changed from the region of stability, there is a certain wavenumberkcat which the onset of plasma‐wave instabilities is expected. Studies are made of the conditions for whichkcvanishes, sincekc= 0 is associated with a special kind of excitations. A proof is given that the growing wave is not on the same branch of the solution to the dispersion relation as the usual plasma wave.

ISSN:0031-9171    

DOI:10.1063/1.1706513

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The conductivity of a turbulent plasma parallel to a magnetic field is determined. The plasma is assumed to be homogeneous and the motion of ions is neglected. The ordinary magnetohydrodynamic equations are used. The nonlinear contribution of the product of density and the electric field to the dc conductivity is expressed in terms of the density fluctuations of the plasma. Both weakly ionized and fully ionized plasmas are considered. The nonlinear effect is present either in a weakly ionized plasma or in a fully ionized plasma with adiabatic waves. For example, in a weakly ionized plasma, the conductivity is reduced by the factor 1 ‐ ⅓Swithout a magnetic field, and is reduced by the factor 1 ‐Swith a strong magnetic field whereS½is the ratio of ac rms value of the density to the dc density. The noise electric fields are found to increase with external dc electric field, especially for a high magnetic field.

ISSN:0031-9171    

DOI:10.1063/1.1706514

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Differential equations and their solutions for the formation of a high‐energy plasma by the injection and trapping of energetic atoms in a magnetic‐mirror geometry are discussed. The present approach differs from previous treatments in that the finite orbit size of the ions and the spatial dependence of the trapping process are included in the equations. By including the spatial dependence it was possible to evaluate the effect of charge exchange of trapped ions with neutral‐beam atoms. Although not affecting the total number of trapped ions, this process results effectively in a change of the mean radial position of the ions. The effect on plasma growth rates of charge exchange of the trapped ions with beam atoms was found to be essentially negligible. The solutions for ion density vs time exhibit growth rates similar to those obtained when the plasma density is assumed to be spatially constant. Background gas variations during plasma buildup have also been investigated. Under the present set of conditions the effect of ``gas burnout'' and plasma pumping are small, even at high densities.

ISSN:0031-9171    

DOI:10.1063/1.1706515

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Diffusion of the current layer at the surface of a compressible electrically conducting gas in a one‐dimensional pinch is analyzed in the limit of large time. Magnetohydrodynamic equations including finite scalar electrical and thermal conductivities are used, and the degree of ionization is taken to be constant. A parameter, which is proportional to the diffusion speed divided by the sound speed, is used to show that the inertia terms may be discarded in large‐time high‐electrical‐conductivity problems. Some numerical results for the temperature, velocity, and magnetic field within the current layer are presented in terms of a similarity variable. In the cases analyzed the gas boundary is displaced from its infinite conductivity position by an amount which is of the order of magnitude of the current‐layer thickness. Comparison of constant conductivity with temperature‐dependent conductivity results shows that Joule heating at the gas boundary improves confinement if the initial conductivities are low.

ISSN:0031-9171    

DOI:10.1063/1.1706516

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A magnetic field is produced by an electric current in a series of pair coils wound around the discharge tube at regular intervals. The electric current in each coil of the pair differs both in intensity and direction. The lines of force near the tube axis undulate without crossing the wall, while those near the tube wall cross the wall. Thus the high‐temperature plasma can be produced by Ohmic heating in the central region of the field. Experiments were carried out in order to verify the spatial confinement of the plasma in this field. The plasma current flows only within the central region whose mean‐cross‐section diameter is about 3 cm, and the plasma has a sharp boundary. Outside the region there is no current. The spectra from the hydrogen discharge are mainly composed of the pure Balmer series, and the impurity spectral lines are very weak or hardly perceptible. From these experimental results, it can be concluded that the hot plasma is almost perfectly isolated from the stainless‐steel‐tube wall by the Heliotron magnetic field and has very low impurity level.

ISSN:0031-9171    

DOI:10.1063/1.1706517

出版商:AIP    

年代:1962

数据来源: AIP