摘要:

An analytic model has been developed to quantify the effects of magnetic field diffusion on plasmas accelerated by magneticJ×Bforces. We examine the penetration of equilibrium and perturbed magnetic fields into a conducting plasma. Analytic solutions are found for both fields for a power law time dependence of the equilibrium field at the field plasma interface. Results show that wavelengths longer than the magnetic field diffusion length penetrate the plasma shell faster than the equilibrium field. For wavelengths shorter than the magnetic diffusion length the perturbed field remains confined to the original field plasma interface and falls off rapidly inside the plasma. Application to imploding linear plasmas show good agreement with detailed two‐dimensional magnetohydrodynamic simulations.

ISSN:0021-8979    

DOI:10.1063/1.336631

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We propose a model for dye lasers operating at resonance with a non‐Gaussian fluctuating pump parameter. Analytical and numerical results are compared with recent experimental measurements on the intensity fluctuations of a dye laser and with previous theoretical predictions based on a fluctuating pump parameter of finite correlation time.

ISSN:0021-8979    

DOI:10.1063/1.336632

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The structure of hard and adherent surface layers formed by cw laser irradiation in air of zirconium disks is examined by electron microscopy and x‐ray diffraction. A model is proposed for the evolution of the interaction process in this case.

ISSN:0021-8979    

DOI:10.1063/1.336633

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Magnetic effects in eddy current nondestructive method are studied employing an extension of the general ideas of Globus for the magnetization processes of polycrystalline materials. The reversible permeability depends on the residual magnetization of the material. The relation between these two quantities is derived from the Globus model. An expression is derived for the impedance of a single‐turn coil above a ferromagnetic conducting half‐space. From this expression, flaw effects and liftoff effects are analyzed, and theoretical treatment for the evaluation of residual magnetization is described.

ISSN:0021-8979    

DOI:10.1063/1.336634

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The effect of stray circuit inductance on the response of a capacitive‐voltage divider to fast‐rising voltage pulses is investigated. Results obtained from the analysis of the capacitive divider’s equivalent circuit indicate an upper‐frequency limit of only 1% of the natural frequency of the circuit.

ISSN:0021-8979    

DOI:10.1063/1.336635

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A new type of discharge realized in a diode consisting of a concave cathode and a special type of a hollow anode is presented. The concave cathode focuses electrons toward the hollow anode increasing the density of high‐energy electrons and the efficiency of excitation and ionization in the hollow anode. The distinctive arrangement of dark and luminous regions between the cathode and anode has been observed in the discharge.

ISSN:0021-8979    

DOI:10.1063/1.336636

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The properties of GaAs/AlGaAs quantum‐well heterostructures have been investigated using transmission electron microscopy (TEM) together with photoluminescence. Modifications to the reactor are described which allow abrupt interfaces (∼5 A˚) and strong optical emission to be obtained up to 300 K from single layers <40 A˚ thick. TEM and Raman scattering have been used to characterize heterostructures, which has resulted in an optimized gas handling system for precise control of reactant fluxes in a low‐pressure apparatus. The effects of pressure transients, gas‐flow recirculation, and residual aluminum incorporation in thin GaAs films grown over AlGaAs are presented.

ISSN:0021-8979    

DOI:10.1063/1.336637

出版商:AIP    

年代:1986

数据来源: AIP