摘要:

The flow of gas and electric current simultaneously through a tube provides an experimental arrangement for the study of the flow of high‐temperature gases capable of precision measurements and a precise mathematical theory. The precision experimental technique and some initial experimental results together with a simplified theory are presented in this paper. Mean electrical conductivities and kinematic viscosities are given for a number of gases. The arc performance is shown to be predictable with fair precision by a very simple discontinuous model of the plasma properties which is capable of wide exploitation in magnetohydrodynamics.

ISSN:0031-9171    

DOI:10.1063/1.1706556

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Observations of pinch and spiral instabilities of a liquid conductor falling in an axial magnetic field are reported. Measured rates of change of the stream diameter and the spiral radius are given, and a stream ``bifurcation'' phenomenon that was induced by spiral instability is described.

ISSN:0031-9171    

DOI:10.1063/1.1706557

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The behavior of the toroidal plasmoid formed in a theta pinch due to trapping of magnetic field lines has been photographed with an ultra‐high‐speed image‐converter camera. Photographs show the plasma ring rotating about an axis perpendicular to the applied magnetic field. This rotation is seen not only as a possible explanation for the sudden disappearance of the trapped magnetic field, but as a mechanism for accelerating the ions caught in the plasmoid. A preliminary analysis provides an upper bound to the ion energies obtainable through such a mechanism.

ISSN:0031-9171    

DOI:10.1063/1.1706558

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A plasma is considered in which a Maxwellian distribution of electrons with thermal velocityveand drift velocityvDis drifting relative to a Maxwellian distribution of ions with thermal velocityvi. ForvD≲vethe usual ion acoustic waves are stable, however, electrostatic ion cyclotron waves with &ohgr; ≅ &OHgr;iare unstable forvD≳ 5vi. In the case when 5vi≲vD≲ve, andTe/Ti< 2 the electrostatic ion cyclotron waves grow to a nonlinear equilibrium spectrum. This spectrum of waves leads to a diffusion of electrons across the field lines with a diffusion coefficientD= &agr;&rgr;2e&OHgr;e, where &rgr;eis the electron Larmor radius and &OHgr;eis the electron Larmor frequency. &agr;, the ratio of the resulting diffusion coefficient to the Bohm diffusion coefficient, is given by a constant × (vD/ve)5(Te/Ti)2.

ISSN:0031-9171    

DOI:10.1063/1.1706559

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A complete classical derivation of the frequency‐dependent conductivity is presented which properly takes into account collective dynamics. This treatment rests on the joint solution of the first two members of the BBGKY hierarchy, in the plasma limit, when both are able to change on the same time scale. For arbitrary frequencies this leads to an integral equation for the one‐particle distribution function which can be solved by conventional variational and/or numerical procedures. For frequencies high compared to the collision frequency, an explicit statement of the conductivity is possible. This high‐frequency limit is further examined in the limit of small electron to ion mass ratio and these limiting results are compared with those of other authors.

ISSN:0031-9171    

DOI:10.1063/1.1706560

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A two‐body distribution function in a plasma is developed for use in a kinetic equation for the one‐body distribution function. The kinetic equation is obtained for a uniform plasma for circumstances in which the time dependence of higher‐order distribution functions can be assumed to occur within a functional dependence on the one‐particle distribution function. The resulting interaction term is new, in the sense that it contains no divergent integrals, and is considered accurate to first order in (e2/KT&lgr;D). The interaction term is composed of two parts. The first is a Boltzmann collision integral with a Debye‐shielded interaction. The second term is due to the deviation of the shielding cloud from a Debye shield and is of the Fokker‐Planck form, the coefficients of which are finite and well behaved. Because of its form, with a convergent collision integral and convergent Fokker‐Planck coefficients, the solution may be considered a joining of the previous solutions to the problem.

ISSN:0031-9171    

DOI:10.1063/1.1706561

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The relaxation of a small group of fast test electrons as a result of two‐body Coulomb encounters with slowfieldelectrons and ions orbiting in a magnetic field is investigated. The analysis is based upon an asymptotic form of the Fokker‐Planck equation which includes the slowing down in speed as well as the angular scattering of the test electrons. The derivation as well as the analytic solution of this equation is presented, and is used to illustrate a case where collisional relaxation of the test electrons alone is responsible for the formation of a second peak in the one‐dimensional electron velocity distribution. The maximum growth rate for the resulting electrostatic drift instability is calculated in the limit when the second peak is much smaller than the main peak, and is found to be proportional to the ratio of test to field particle density. The results are used to suggest an explanation of the several unstable currentstepsobserved in the stellarator during its crowbarred relaxation phase.

ISSN:0031-9171    

DOI:10.1063/1.1706562

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The interaction between cylindrically symmetric anisotropic plasma column and bounded electro‐magnetic waves is analyzed theoretically. The properties of a cylindrical cavity coaxial with a cold plasma column and a coaxial with a static magnetic field are determined. The shift in the resonant frequency of the cavity‐plasma system is calculated in the high‐electron‐density limit and compared with the numerical solution presented earlier.

ISSN:0031-9171    

DOI:10.1063/1.1706563

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The effect of the temperature of a fully ionized plasma on its conductivity to a radio wave is investigated, taking into consideration the finite wavelength of the radio wave. The order of the effect iskT/(ma2), whereTis the temperature of the gas,mthe mass of an electron,kthe Boltzmann constant,athe phase velocity of the wave. The relativistic effect is not considered.

ISSN:0031-9171    

DOI:10.1063/1.1706564

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The effect of correlations on bremsstrahlung from a plasma is studied by using in Kirchhoff's law an absorption coefficient obtained from a Boltzmann‐Fokker‐Planck equation. A simple derivation of the Fokker‐Planck coefficients is given by relating them to familiar dc coefficients. A dispersion formula giving the principal behavior of the absorption coefficient is obtained from a first iterate solution of the Fokker‐Planck equation, treating the scattering of electrons by ions as a perturbation. The absorption coefficient reduces to the incoherent radiation result at frequencies much higher than the plasma frequency. At the plasma frequency it is greater than the incoherent absorption coefficient by a factor ofO[(n&lgr;D3)12], wherenis the electron density and &lgr;Dis the Debye length. The effect of surface reflections on the net emission is discussed.

ISSN:0031-9171    

DOI:10.1063/1.1706565

出版商:AIP    

年代:1962

数据来源: AIP