摘要:

The moment equations, neglecting the heat‐flow tensor, have been used to study the wave propagation in a plasma consisting of electrons and singly charged ions, in a magnetic field, with anisotropic pressure tensors for both components. Two cases of wave propagation along the magnetic field and perpendicular to it have been worked out separately. In the first case of propagation along the magnetic field, the waves separate into a pure longitudinal and a pure transverse wave, the second of these only being affected by the anisotropy of the pressure tensor. Conditions are deduced under which the anisotropy of the pressure tensor can alter the propagation conditions of the waves. Attention is also given to the possibility that it can give rise to an instability. One important result which follows for magnetohydrodynamic waves is that an anisotropy in the electron pressure can give rise to an instability of the Alfve´n waves. In the other case of the propagation across the field, the waves separate into a pure transverse wave and a wave which represents a combined longitudinal and transverse wave. The second of these is unaffected by the anisotropy of the pressure tensor. For the pure transverse wave, conditions are obtained under which instability can arise.

ISSN:0031-9171    

DOI:10.1063/1.1706711

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The long‐wavelength modes of excitation of a two‐component plasma in a steady magnetic field are examined. Two linearized Boltzmann equations are given with collision terms which are coupled through the difference in temperatures and difference in velocities of the two gases. A formal means of classification of phenomena is described in terms of the nature of the roots aboutk= 0. Two types of behavior are uncovered: magnetohydrodynamics, which includes finite phase‐speed phenomena neark= 0; and plasma electromagnetics, which includes infinite‐phase‐speed phenomena neark= 0. The dissipative effects of collisions are included. In the limit of vanishing collision frequency, roots previously obtained are recaptured. The relevance of the pertinent domains are discussed and the complex interplay between the ``fast'' and ``Alfve´n'' modes of magnetohydrodynamics and the plasma‐magnetic modes of the plasma electromagnetic domain is demonstrated. Equations macroscopic in appearance are derived which include the effects of the initial configuration. In the limit of large collision frequency these equations reduce to standard forms. The dispersion of theNth‐order Larmor resonance is given which includes the effect of the mass ratio.

ISSN:0031-9171    

DOI:10.1063/1.1706712

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An annular source is described which approximates a one‐dimensional geometry. Characteristic behavior is given, primarily for one set of operating parameters. A fast‐acting valve injects 0.3 cc STP hydrogen, and capacitor firing is timed to permit operation in the ``slug'' mode. Photomultiplier data indicate a luminous front acceleration (for 40 cm) to a muzzle velocity of 103 cm/&mgr;sec; position probes yield 74 cm/&mgr;sec. The data appear to verify a hydromagnetic acceleration model, based on analog computation for a 0.06‐&mgr;g slug (which is more than half the gas available in the annulus). The theoretically expected momentum is 6.2 dyn‐sec; experiment yields 11.4 dyn‐sec. Tentative number density and electron temperature are 3 × 1014/cc and 3.6 eV, respectively, the latter obtained by a double Langmuir probe. The discussion includes efficiency considerations and a brief examination of the ion and electron collisional and gyromagnetic parameters.

ISSN:0031-9171    

DOI:10.1063/1.1706713

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The stability of a positive column in a longitudinal magnetic field is investigated by linearization of the macroscopic equations of motion and continuity for ions and electrons. The treatment is more general than similar calculations by Kadomtsev and Nedospasov and Hoh, in that diffusion and magnetic field interaction terms are included in the ion equation of motion, and also in that the equations are solved in a rigorous manner without anya prioriassumptions regarding the form of the radial dependence of the perturbations of density and potential.In the one example calculated, for the helical instability, an important result is the existence of a finite perturbed potential at the wall radius. The boundary between stability and instability as a function of longitudinal electric and magnetic fields is shown graphically, along with the wavelength and frequency of the helical mode at the critical value of the magnetic field.

ISSN:0031-9171    

DOI:10.1063/1.1706714

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The motion of charged particles in electromagnetic fields under extremely nonadiabatic conditions is investigated. This is the case, e.g., if the particle passes through a region of vanishing magnetic field, either in space or in time. In fields of axial symmetry, the constancy of the canonical angular momentum lends the tool for this investigation. Strict laws for flux conservation are derived including rapid changes of fields in space and time. Particle injection into cusped geometries is studied and compared to experimental results. Particle motion under magnetic‐field reversal in time is investigated and compared to findings in &thgr;‐pinch experiments under field reversal. A simple self‐consistent model for such a particle motion is developed leading to the automatic formation of anElayer as a consequence of field reversal.

ISSN:0031-9171    

DOI:10.1063/1.1706715

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

It is shown that in the absence of a magneto‐static field, in the case of high frequency and high impedance, the steady force exerted by an rf field on a plasma is essentially proportional to the energy density gradient of the rf electric field. As an example, a simple rf plasma propulsion problem is solved, involving a plasma and an electrode structure, both of finite extent. The solution is consistent with experimental results which show that a finite body of plasma whose density is greater than critical is pulled in the direction of increasing electric field whereas a plasma whose density is less than critical is pushed in the direction of decreasing electric field.

ISSN:0031-9171    

DOI:10.1063/1.1706697

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A probe is considered in a magnetic field so strong as to impair collective transverse drifts. Then the charges supplied to the probe come mainly from a long tube of force, whose radius is about one Larmor radius larger than the probe. Assume that there is acting a diffusion process, more efficient than ordinary drifts, which continuously exchanges particles between the inside of the tube of force and the rest of the plasma. In a previous paper we have proposed a one‐dimensional model of this process, leading to an integro‐differential Poisson's equation, which has now been fully investigated in the case of slow diffusion. The solution consists of a chargeless, slowly decaying potential which describes the geometrical screening effect of the probe; while in the sheath an approximate boundary‐layer solution matches with the probe's potentialVP. The asymptotic relation between the current collected andVPis computed. This model may be suited to the case of diffusion due to random wave fields.

ISSN:0031-9171    

DOI:10.1063/1.1706698

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.1706699

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.1706700

出版商:AIP    

年代:1962

数据来源: AIP