摘要:

The high frequency conductivity of a magnetoplasma is calculated from a fully convergent quantum mechanical kinetic equation. The frequency of the perturbing field is not restricted to frequencies low in comparison with the plasma frequency nor is the temperature of the unperturbed plasma restricted to values low in comparison with a Rydberg.

ISSN:0031-9171    

DOI:10.1063/1.862178

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The full three‐dimensional Maxwell–Vlasov system is solved as a boundary value problem for systems contained by plane, perfectly reflecting boundaries. The spatial behavior of the fields seems to contradict some commonly made assumptions. In particular, for low frequency, &ohgr;≪&ohgr;p, and typical plasma densities, all components of the electric and magnetic fields decay to zero on a scale which is no larger and 0.05 cm.

ISSN:0031-9171    

DOI:10.1063/1.862155

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The transport of neutral hydrogen atoms in a hydrogen plasma slab is considered. After making a reasonable approximation for the charge exchange rate, analytic solutions for the neutral distribution function are obtained which depend on one spatial and three velocity variables. To obtain these, a condition must be imposed that implies uniform electron and ion temperatures. Specular reflection of the neutrals at the boundaries is considered. Solutions associated with the diffusion approximation are also given and the condition for its validity is discussed. The solutions are evaluated for the case of Maxwellian ion distribution functions.

ISSN:0031-9171    

DOI:10.1063/1.862156

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Ion density fluctuations and the ion velocity distribution function in the presence of the current‐driven electrostatic ion cyclotron instability are determined using resonance fluorescence of the ions. The optical line intensity modulation shows that the ion density modulation can be as large as 90%. From the Doppler broadening of the lines it is found that the distribution function of ions heated by the unstable ion cyclotron waves is Maxwellian with an uncertainty of 5%.

ISSN:0031-9171    

DOI:10.1063/1.862157

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

One problem with ion‐acoustic waves is that sometimes they are observed to be reflected from discharge tube walls, and sometimes to be absorbed. Theoretical computation reveals that a velocity gradient produced by a density gradient plays a significant role in the reflection. The velocity gradient produces a subsonic−supersonic transition and long wavelength waves are reflected before reaching the transition while short wavelength waves penetrate over the transition and are absorbed in the supersonic flow plasma.

ISSN:0031-9171    

DOI:10.1063/1.862158

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The nonlinear saturation amplitude of the dissipative trapped electron instability is calculated. Comparison is made with an experiment carried out in linear mirror geometry and near threshold, with only a single mode predominating. A model in which the untrapped electrons respond in a Boltzmann fashion yields good agreement. A model in which Landau damping is included predicts saturation amplitudes much smaller than observed. The first model seems appropriate for linear geometries while the second may apply to closed devices.

ISSN:0031-9171    

DOI:10.1063/1.862159

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The effect of magnetic shear on electrostatic Bernstein waves is investigated. It is shown that shear leads to nonlocal eigensolutions and the convective damping of the Bernstein waves. The threshold for the parametric instability of a magnetosonic wave into two Bernstein waves in a multispecies plasma is increased by shear. For a magnetosonic heating experiment conducted on a tokamak comparable to the Doublet III device at General Atomic, the parametric instability may still be excited despite the plasma inhomogeneities provided the pump wave amplitude exceeds a critical value to be estimated in this paper.

ISSN:0031-9171    

DOI:10.1063/1.862160

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A simple problem exhibiting intrinsic stochasticity is treated: the motion of a charged particle in a uniform magnetic field and a single plane wave. Detailed studies of this wave‐particle interaction show the following features. An electrostatic wave propagating obliquely to the magnetic field causes stochastic motion if the wave amplitude exceeds a certain threshold. The overlap of cyclotron resonances then destroys a constant of the motion, allowing appreciable momentum transfer to the particles. A wave of large enough amplitude would thus suffer severe damping and lead to rapid heating of a particle distribution. The stochastic motion resembles a diffusion process even though the wave spectrum is monochromatic. The methods of this paper should be useful for other problems showing stochasticity such as superadiabaticity in mirror machines, destruction of magnetic surfaces in toroidal systems, and lower hybrid heating.

ISSN:0031-9171    

DOI:10.1063/1.862161

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The dispersion of the sidebands of a large amplitude plasma wave has been measured. Sidebands propagate according to a beam‐plasma type dispersion. Sideband dispersion is calculated with a quasi‐linear theory using the locally measured time‐averaged electron velocity distribution. This model assumes that the large wave and the sidebands interact primarily through the time average of the perturbation the large wave causes in the velocity distribution. The measured sideband dispersion agrees with the predictions of this model.

ISSN:0031-9171    

DOI:10.1063/1.862162

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A plasma wave with an oscillating amplitude and phase occurs in two commonly studied situations, the beam‐plasma interaction and the launching of a large‐amplitude wave in a Maxwellian plasma. Electron motion in such a wave is either regular or stochastic. Theoretical study shows that regular motion can exhibit a phase‐locking effect, which explains the persistence of amplitude oscillations observed in simulations and experiments. An additional (’’test’’) wave of moderate amplitude can prevent phase‐locking, causing stochastic motion instead, and thereby destroy the amplitude oscillations. The effects studied are also relevant to the theory of sideband instability.

ISSN:0031-9171    

DOI:10.1063/1.862163

出版商:AIP    

年代:1978

数据来源: AIP