摘要:

This paper reports measurements of the shape of the cathode dark space (CDS) of a dc sputtering system. Special attention was given the CDS enveloping the cathode since this region influences the sputtering of the cathode periphery. A Langmuir probe was used to map the CDS negative glow boundary which was found to remain unchanged with cathode‐anode spacing until the anode neared the CDS boundary. Glass substrates placed on the anode also influenced the CDS shape. The Langmuir probe current‐voltage characteristic changed with time until the probe was completely coated with metal sputtered from the cathode. The coated probe gave reproducible results over a long period of time.

ISSN:0021-8979    

DOI:10.1063/1.1662528

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

For a magnetically confined plasma the effect of laser pulse rise time on heating is considered theoretically. The hydrodynamic equations are solved analytically in the asymptotic limit. We find that for a certain range the laser pulse energy requirement is quite sensitive to the rise time. By properly choosing the laser pulse rise time, the energy requirement can be decreased as much as 25%. The maximum radiation flux density is however not very sensitive and increases only slightly. It seems that fast‐rising laser pulses are superior as far as flux is concerned but are inferior to slow‐rising laser pulses from the point of view of energy requirement.

ISSN:0021-8979    

DOI:10.1063/1.1662529

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

General properties of plane‐wave scattering by inhomogeneous anisotropic obstacles of arbitrary shape and of arbitrary number are presented on the basis of the reciprocity relations and the forward‐scatter theorem. For the composite obstacles with symmetrical tensor characteristics, it is shown that interchange of the direction of incidence and that of observation keeps the bistatic scattering cross section unchanged on a condition, and that reversion of the incident direction gives the same extinction cross sections (or the same scattering cross sections in case of lossless obstacles) on the other conditions. For the composite obstacles with unsymmetrical tensor characteristics the following results are shown: Interchange of the direction of incidence and that of observation accompanied with transposition of all the tensor characteristics keeps the bistatic scattering cross section unchanged on a condition. Moreover, reversing the incident direction and transposing all the tensor characteristics, we have the same extinction cross sections on the other conditions. In case some of the obstacles are perfectly conducting, we have the same results as before. For the two‐dimensional problems which can be decomposed intoEwave andHwave, the above‐mentioned results hold without condition.

ISSN:0021-8979    

DOI:10.1063/1.1662530

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A steady two‐dimensional magnetohydrodynamic boundary‐layer control with uniform suction or injection is investigated. The transverse magnetic field is fixed to the semi‐infinite flat plate and the electric field is assumed to be zero. A nonsimilar boundary‐layer equation is solved numerically by a difference‐differential method originated by Hartree and Womersley and improved by Katagiri. The velocity profiles and the coefficient of the skin friction are computed for various values of magnetic parameter and suction/injection parameter. The graphical plots indicate increasing boundary‐layer thickness and decreasing skin‐friction coefficient with increasing magnetic parameter, and also decreasing boundary‐layer thickness and increasing skin‐friction coefficient with increasing sunction/injection parameter. The magnetic field is found to be rather efficient in modifying the boundary layer, especially with the help of a proper seeding material.

ISSN:0021-8979    

DOI:10.1063/1.1662531

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The propagation of cyclotron harmonic waves in a cold‐cathode reflex discharge has been studied over a broad range of experimental parameters. Electron temperatures obtained from the waves and spectroscopic temperatures are in agreement but are an order of magnitude lower than double Langmuir probe temperatures. A non‐Maxwellian electron velocity distribution for the plasma is suggested which can explain these results.

ISSN:0021-8979    

DOI:10.1063/1.1662532

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A new configuration of coaxial plasma accelerator with self‐energized magnetic compressor coil attached is described. It is shown that the circuit may be treated theoretically by analyzing an equivalent circuit mesh. The results obtained from the theoretical analysis are shown to compare favorably with the results measured experimentally. Using this accelerator configuration, glass beads of 125‐&mgr; diameter were accelerated to velocities as high as 11 km/sec, while 700‐&mgr;‐diam glass beads were accelerated to velocities as high as 5 km/sec. The velocities are within the hypervelocity regime of meteroids.

ISSN:0021-8979    

DOI:10.1063/1.1662533

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Analytical treatments of the space‐charge spread of cylindrical beams have been based upon a number of restrictive assumptions. Most of them can be removed and a higher accuracy attained with the help of a suitable relation connecting motion and Maxwell's equations. As previous treatments appear as paraxial approximations, third‐order formulas applying to arbitrary field forms have been carried out.

ISSN:0021-8979    

DOI:10.1063/1.1662534

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Equations describing the dependence of the dwell times on the applied voltage of thin exploding wires whose restrikes are initiated at the exterior or the interior of the exploded wire are derived, using the energy equation for the ionized gas surrounding the wire and the Paschen law for the sparking potential, respectively. A comparison of the computed and the experimentally obtained dependences of dwell times on the applied voltage was made for thin constantan and tungsten wires.

ISSN:0021-8979    

DOI:10.1063/1.1662535

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The refractive index of water under conditions of dynamic loading up to a pressure of about 10 kbar has been measured by a geometrical refraction method with the high‐speed Kerr‐Cell camera system. Geometry of light transmission through the spherical front of shocked water has been worked out by applying Snell's law and the simple assumption of the zero‐density gradient in the disturbed water and an attempt has been made to calculate the shock pressure underwater therefrom. The results obtained here are found comparable within 0.4% with those determined by Zeldovich employing the method of reflectivity.

ISSN:0021-8979    

DOI:10.1063/1.1662536

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A new experimental technique has been developed for the study of the dynamic tensile strength of liquids. The liquid is confined between a solid plate and a stretched aluminized Mylar film. Pulsed electron beam deposition in the plate generates a stress wave which traverses the liquid and gives a high tensile stress during reflection at the Mylar‐covered free surface. Interferometric analysis of the motion of the Mylar film provides a sensitive measure of the stress‐wave‐liquid interaction. The technique has been used to determine a dynamic tensile strength for glycerol at room temperature of 0.6±0.1 kbar from 5 to 23 kbar/&mgr;sec. No variation of tensile strength with stress rate was found.

ISSN:0021-8979    

DOI:10.1063/1.1662537

出版商:AIP    

年代:1973

数据来源: AIP