摘要:

Numerical computations have been performed using rigorous kinetic theory to determine the transport properties such as viscosity, thermal conductivity, electrical conductivity and electron diffusion coefficient, for an argon plasma at elevated electron temperatures (5000°K to 20 000°K) and pressures (10−3atm to 103atm) with the ratio of electron temperature to heavy particle temperature ranging from 1.0 to 3.0. The values for the transport properties for a plasma in thermal equilibrium could be obtained as a special case from the present scheme of calculations. Comparison with previous results for the special case of a plasma in thermal equilibrium shows good agreement.

ISSN:0031-9171    

DOI:10.1063/1.861788

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The physics of induced Thomson scattering is studied for the general case of coherent fields. The analysis is purely classical. A direct evaluation of the radiation emitted by a resonant particle leads to a classical interpretation of the wave‐conversion process. The relation between induced scattering and spontaneous scattering is discussed in classical terms.

ISSN:0031-9171    

DOI:10.1063/1.861789

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Neoclassical transport for an elliptic tokamak in all collisional regimes is investigated by the technique of partitioning the velocity space. It is found that in a tokamak of moderate elongation, particle and ion heat confinement times are increased by a factor of &sgr;2, where &sgr; is the ratio of the vertical minor radius to the horizontal minor radius. Ripple diffusion in an elliptic tokamak is also studied. Ion heat conductivity due to ripples is reduced by a factor of approximately &sgr;2.

ISSN:0031-9171    

DOI:10.1063/1.861790

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A scaling law governing the cooling of a finite‐length column due to electron thermal conduction loss at the column ends, where the magnetic field lines are intercepted by a cold material wall, is derived. In addition to the electron temperature, both the electron number density and the magnetic field strength are allowed to vary along the field lines. It is shown that the cooling of the column is not very sensitive to moderate spatial variations of number density and magnetic field strength and is well represented by a characteristic cooling time given by &tgr;0= (5/2)nL2/K0, whereLis the column half‐length andnandK0are the number density and coefficient of thermal conductivity at the midplane.

ISSN:0031-9171    

DOI:10.1063/1.861791

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

It is shown that self‐generated magnetic fields can play a significant role in laser light absorption. Even normally incident light is then resonantly absorbed via the excitation of upper hybrid oscillations. Computer simulations and theoretical estimates for this absorption and the concomitant harmonic generation are given for parameters characteristic of some recent experiments.

ISSN:0031-9171    

DOI:10.1063/1.861766

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The group velocity resonance cone in a drifting warm magnetoplasma is studied. Potential of a point charge is calculated in such a plasma. It is found that for a drift velocityVd<Vt/tan &Vthgr;c, whereVtis the electron thermal velocity and &Vthgr;cis the cold cone angle, the downstream interference structure is useful for diagnostics of electron temperature using the formulae of a stationary plasma. The downstream interference pattern is appreciably modified forVd≳Vt/tan &Vthgr;c. The upstream interference pattern is appreciably modified even for small drifts. ForVd≳Vt/tan &Vthgr;c, a new interference pattern appears for angles given by &Vthgr;c<&Vthgr;<180°−&Vthgr;c. This new interference pattern is useful from the view point of measuring field‐aligned drifts in laboratory and space plasmas.

ISSN:0031-9171    

DOI:10.1063/1.861767

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The spontaneous synchrotron emissivity from a high density, weakly relativistic plasma in thermal equilibrium is discussed. Thermal effects on the dielectric polarization of the plasma are included in the analysis, and the result is compared with computations of the emissivity based upon the cold plasma approximation. A numerical analysis is performed for frequencies in the vicinity of both the electron cyclotron frequency and the upper hybrid resonance. Significant modifications to the synchrotron emissivity in the cold plasma approximation are found in both of these frequency regimes.

ISSN:0031-9171    

DOI:10.1063/1.861768

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A new formulation of the nonlinear coupling of coherent waves described by the Vlasov equation is presented. This is used to derive the parametric growth rate for the down conversion from a lower hybrid pump wave to ion‐Bernstein waves. It is found that the maximum growth rate for this interaction is larger than that for any other resonant interaction. The relevance of this to the current interest in lower hybrid heating of plasmas is discussed.

ISSN:0031-9171    

DOI:10.1063/1.861769

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The spatial growth rate of the cross‐field ion acoustic instability is measured in an ion‐beam‐plasma system with a transverse magnetic field. By taking into account the finite width of the plasma, the ion beam temperature, and ion‐neutral collisions, good agreement with the theoretical growth rate is obtained when (i) the normalized wavenumberk&ngr;&rgr;eis varied and (ii) the magnetic field direction is varied through a small angle about the direction perpendicular to the beam.

ISSN:0031-9171    

DOI:10.1063/1.861770

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

An experimental study of ion acoustic plasma turbulence in a collision‐dominated positive column is presented. Linear theory predictions, which include ion Landau damping and the effects of a dc electric field, are shown to agree with measured values of convective growth rates. At high levels of turbulence, interferometric methods are not useful for studying the wave phase characteristics. Instead, the detailed spectral density for two‐dimensional wave propagation,S(k,&ohgr;), is obtained by performing a two‐dimensional spatial Fourier transform on sampled values of the frequency sweeps of the complex cross‐power spectral density. The instability is found to be essentially one‐dimensional, with the waves propagating along the direction of the electron drift velocity. The spectra are integrated numerically, and the energy density obtained is discussed in terms of two nonlinear models of saturated state of the instability. Time‐ and frequency‐resolved power spectra are measured by sampling techniques, and compared to the predictions of linear theory. Temporal evolution of the phase characteristics is measured by a novel diagnostic technique.

ISSN:0031-9171    

DOI:10.1063/1.861771

出版商:AIP    

年代:1977

数据来源: AIP