摘要:

The effect of an ionized or un‐ionized background on magnetohydrodynamic instabilities in a Z pinch is considered. It is shown that the growth rate may be reduced by at least one or two orders of magnitude even though the background pressure is small compared with the pinch pressure. The stabilizing effect of launching shocks in the background gas is considered qualitatively. It is shown that it is theoretically possible to construct equilibria such that confinement for a Lawson time can be attained, but only for backgrounds of roughly liquid density. Also, it is shown that lightning discharges are stabilized by the presence of the background atmosphere.

ISSN:0031-9171    

DOI:10.1063/1.1694475

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The effects of Krook model collisions on the electron‐electron two‐stream instability were investigated by means of a computer code. It was found that a collision frequency small in comparison with the electron plasma frequency delays the onset of saturation of the instability, decreases the total electrostatic field energy at saturation, and lowers the linear growth rates. This last effect is in very good agreement with the growth rates predicted by the linear theory of the Krook equation.

ISSN:0031-9171    

DOI:10.1063/1.1694476

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Using numerical simulation, it was found that, with the inclusion of thermally‐generated magnetic fields, about 3 × 104neutrons are produced in 2 nsec and the electron temperature rose as high as 15 keV in a target heated by a 4‐nsec, 80‐J laser pulse.

ISSN:0031-9171    

DOI:10.1063/1.1694477

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The current‐voltage characteristics of cylindrical probes in a high velocity collisionless plasma flow have been investigated experimentally and theoretically. The plasma was generated by a focused laser pulse incident on a metallic target in vacuum, with an expansion velocityU, such thatkTi/Mi ≪ U2 < kTe/me. An analysis, developed from a stationary plasma analog to the flowing case, demonstrated a failure of plasma shielding of probe potential in the electron attracting region, even when&lgr;D = (kTe/4&pgr;nee2) 1/2 ≪ R, the probe radius. Under these conditions, modifications of relatively simple previous treatments were found to be valid for computing electron current to a probe. The electron characteristics derived from the present analysis agree well with experimental results for a voltage range of typically− 5 kTe /e < V < + 3kTe/earound plasma potential. The ion and electron portions of the characteristics are consistent with each other and with independent diagnostic measurements.

ISSN:0031-9171    

DOI:10.1063/1.1694478

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Numerical calculations of field line trajectories and drift orbits show that small field perturbations can destroy the single particle confinement in bumpy tori. Criteria are derived for tolerable field errors assuming neoclassical diffusion.

ISSN:0031-9171    

DOI:10.1063/1.1694479

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Arbitrary one‐point moments of the concentration of the chemical reactant in a turbulent flow are related to the Lagrangian position probability density. The results are extended to multicomponent reactions. Molecular diffusion effects are neglected in the analysis.

ISSN:0031-9171    

DOI:10.1063/1.1694480

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Elementary solutions for the linearized BGK model equation are used to calculate accurate values for the temperature slip coefficient with arbitrary accommodation at the surface. Results are compared to those of Loyalka and of Welander.

ISSN:0031-9171    

DOI:10.1063/1.1694481

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Measurements have been made of the absorption of CO2laser light at 10.6&mgr;mby a fully ionized argon plasma. These values are compared with the theoretical values which are calculated from the measured electron densities and temperatures in the plasma.

ISSN:0031-9171    

DOI:10.1063/1.1694482

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

It is shown that a nonuniform collisionless magnetoplasma may absorb power from an external source through the excitation of a large number of radially varying electrostatic modes. If a randomizing mechanism is present, irreversible plasma heating can take place.

ISSN:0031-9171    

DOI:10.1063/1.1694483

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The two‐fluid theory of laser‐driven nonlinear plasma instabilities is reformulated to describe imperfectly coherent radiation. For a particular model of the laser noise, the modified dispersion relation is found and a simple estimate for the increase in stability threshold obtained.

ISSN:0031-9171    

DOI:10.1063/1.1694484

出版商:AIP    

年代:1973

数据来源: AIP