摘要:

The stability of a dense plasma (negligible skin depth) confined by a rotating magnetic field which is parallel to the surface is analyzed for plane and cylindrical geometries. This analysis culminates in an integrodifferential equation for each mode of deformation. Specific properties of the plasma enter only through the normal acoustic impedance. The concept of average stability is introduced. Very general restrictions on the acoustic impedance of the plasma are introduced which allow the derivation of various stability criteria. These criteria are applied to different cases of interest. The plasma is described successively by a fluid model and a free particle model. Numerical estimates of the frequency needed to achive stability for each mode are given.

ISSN:0031-9171    

DOI:10.1063/1.1762090

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A balanced magnetic probe technique has been used to determine the drive force acting on the plasma sheath during the first pinch. The sheath motion was studied with the probe technique, and with image converter framing pictures. The sheath mass was determined from the velocity and the time integral of the drive force. The results indicate an average pickup coefficient of 0.82 ± 0.06 for the first half of the pinch. Electron density and temperature were determined during the first half of the pinch by measurement of the H&bgr;line profile. Combination of the spectroscopic and mass data indicates an average sheath ionization lower than predicted by theory, but the experimental error in the ionization determination precludes a definite conclusion to this effect.

ISSN:0031-9171    

DOI:10.1063/1.1762091

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A formula is derived for the average rate of energy loss suffered by a charged particle moving in a helical orbit in a homogeneous medium. In a cold, magnetized plasma it is shown that the Cˇerenkov excitation of the whistler and ion cyclotron waves depends critically on certain characteristic wave speeds relative to the component of the particle's velocity parallel to the magnetic field. The power spectrum of Cˇerenkov radiation exhibits sharp peaks not only at the frequencies of the lower and upper hybrid resonances but also at those frequencies at which the ray phase velocity equals the particle's velocity,v∥, parallel to the magnetic field. An intriguing feature of this radiation is that the more slowly the particle moves along the magnetic field, the greater is the emitted radiation; the power emitted in the whistler mode also becomes large whenv∥equals the group speed of those waves that are beamed along the magnetic field. By using a simple graphical construction one can readily locate those directions in which the angular distribution of synchrotron radiation is sharply peaked.

ISSN:0031-9171    

DOI:10.1063/1.1762092

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The manner in which a pumping wave of high amplitude can produce parametric instabilities in a plasma is investigated. A very simple derivation of the nonlinear polarizabilities is given for the case when the pumping wave is homogeneous. From this nonlinear polarizability, a derivation of the accurate nonlinear dispersion relation is given. One finds unstable waves by solving this nonlinear dispersion relation. The critical level of the pumping wave is very much reduced if the proper modes allow carrying out the stimulated Brillouin effect. A pumping wave with a cyclotron resonance gives a particularly low critical level.

ISSN:0031-9171    

DOI:10.1063/1.1762093

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is shown that Stokes law for a charged sphere of radiusRmoving slowly in a compressible polarizable liquid isF=6&pgr;Ru&eegr;1−135∂&rgr;∂p|T&agr;0&egr;0ez4&pgr;&egr;R22

ISSN:0031-9171    

DOI:10.1063/1.1762095

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Expressions are given for the additional matrix elements necessary for the third approximation to the viscosity of multicomponent mixtures. The improved accuracy of this approximation is considered for several gas models.

ISSN:0031-9171    

DOI:10.1063/1.1762096

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The theoretical result for the asymptotic decay of a spherical shock wave is shown to provide a useful extrapolation into that range in which numerical integration is unreliable and/or expensive, but where the decay is still significantly greater than acoustical.

ISSN:0031-9171    

DOI:10.1063/1.1762097

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Numerical solutions of the Vlasov equation for plasma wave propagation through a sheath into a nonuniform plasma have been obtained. A strong wave is excited for frequencies slightly above the plasma frequency at the sheath edge.

ISSN:0031-9171    

DOI:10.1063/1.1762098

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Several modifications are made to the quasi‐linear equations of Harris which distinguish between weakly and strongly damped modes and between the tail and body of the particle distribution function.

ISSN:0031-9171    

DOI:10.1063/1.1762099

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An outline is given of the theory underlying a class of low‐frequency oscillations in partially ionized gases that are described by the operation of the plasma continuity equations.

ISSN:0031-9171    

DOI:10.1063/1.1762100

出版商:AIP    

年代:1967

数据来源: AIP