摘要:

Gas bubbles in charged regions of a dielectric liquid move away from high fields. They do not acquire a net charge of their own, but are moved by electrical pressure gradients and polarization forces. The phenomenon is of interest for a variety of applications.

ISSN:0021-8979    

DOI:10.1063/1.1729571

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The diffraction of eigen‐loss electrons is examined in some detail. It is shown that the collision zone with a crystal is sufficiently diffused that a significant fraction (10% atE= 105V) ofE1=E−&dgr;Eelectrons are produced outside the crystal boundaries. These electrons behave like an incident beam of energyE1and appear to be responsible for Watanabe's observations with an energy selecting electron microscope.

ISSN:0021-8979    

DOI:10.1063/1.1729572

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A helium‐neon optical maser tube with high‐quality fused quartz windows at the Brewster angle supports oscillations between external plane mirrors at 6328 Å, 1.15 &mgr;, and 3.39 &mgr;, producing over 40 mW at 1.15 &mgr; and 28 mW at 3.39 &mgr; in the dominant TEM00mode. Calculations of Fox and Li are verified by means of apertures inside the resonator. Patterns made with various obstacles in the resonator bear a blurred resemblance to those made with the same obstacles in the 1‐cm beam outside the resonator.

ISSN:0021-8979    

DOI:10.1063/1.1729573

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The balance between diffusion and ion migration in dc discharges in certain mixtures of metal vapors and rare gases produces a very sharp line of demarcation between the region containing only the rare gas and the region containing both the rare gas and metal vapor. Although the formation of such a sharp boundary depends in a complex way upon the elastic and inelastic cross sections for electron‐atom collisions, it can be used in a simple way for the determination of certain discharge parameters.If a cold spot with a well‐defined location is provided near the cathode end of the positive column, the distance from the cold spot to the line of demarcation and the potential drop across the tube are, at a given current and rare gas pressure, accurately reproducible functions of the cold‐spot temperature. If these functions are determined, and if the neutral‐atom diffusion coefficient and positive ion mobility are known for the metal vapor in the rare gas, a simple theory yields values for electron concentration, electron mobility, and the ratio of electron to ion current as a function of pressure of the metal vapor.Detailed application has been made to a hot‐cathode neon‐mercury discharge over a range of mercury pressure from 2.5 to 25&mgr; and for a neon pressure of 3 Torr. For a 500‐mA dischargen−is about 3.5×1011cm−3, &mgr;−ranges from 1.4 to 2.5×106cm2/V sec, and &mgr;−/&mgr;+, from 800 to 1800.

ISSN:0021-8979    

DOI:10.1063/1.1729574

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Empirical data concerning the Curie temperatures of binary Co‐Ni, Fe‐Ni, and Fe‐Co alloys is used to predict the Curie temperature of ternary fcc Fe‐Ni‐Co alloys. The predicted values of the Curie temperature of the ternary alloys agree within 30° over the entire range of fcc structure with much better agreement over most of the range of concentrations. The model used to make this prediction is an extension of the approach introduced by Zener and developed by Carr.

ISSN:0021-8979    

DOI:10.1063/1.1729575

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Pulsed microwave power is used to produce breakdown in a constricted 3‐cm waveguide containing oxygen gas in the pressure range from 15 to 25 mm Hg. The breakdown characteristics are studied as a function of the flow velocity of the gas. The power necessary to maintain the discharge after it has been initiated increases with flow velocity up to a critical velocity because the electron density at the constriction is reduced by the flow. Beyond the critical velocity the necessary power decreases with flow velocity. This latter phenomenon is believed to be due to ``back flow'' of the gas.

ISSN:0021-8979    

DOI:10.1063/1.1729576

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Theoretical and experimental studies of the duo‐emitter diode are described. In this diode an electron emitter and an ion emitter are facing each other. Two space‐charge configurations have been found for this diode, one where the interelectrode space is occupied by a dense plasma and one where potential barriers for the emitted particles exist near the emitters. The experiment, using a low‐pressure cesium‐vapor diode, gives results in good agreement with theory.

ISSN:0021-8979    

DOI:10.1063/1.1729577

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

This paper presents the results of bombarding the (100), (110), and (111) surfaces of aluminum single crystals with a narrow beam of 8‐kV argon ions. The crystals were tilted at the angles required to bring [110], [100], [112], and [111] directions parallel to the beam. The experiments were designed to study the effect of incident ion direction on ejection directions and etching rates.Ejection directions, as determined from the positions of deposits on hemispherical collectors, were found to be independent of incident ion direction for a given surface orientation. The quantity of material ejected along equivalent ejection directions was observed to decrease as the angle of deviation between the incident ion beam and the ejection direction increased. The principal ejection directions observed were [110]. Apparent [116] ejection directions were observed when (110) and (111) surfaces were bombarded. These were caused by an abrupt deflection of momentum from [110] directions of the crystal to directions close to [110] of elementary twins. These are formed by surface atoms in twin positions on (111) surfaces developed, in the case of the (110) surface, during bombardment. The [110] directions of an elementary twin are parallel to certain [114] directions of the crystal, and, had multilayer twins been formed, the resulting ejection would have been along apparent [114] directions as a result of Silsbee focusing. Ejection along apparent [116] directions was not observed from (100) surfaces presumably because predominant [100] surface grooves produced by bombardment could not contain (111) facets. Under these conditions [100] ejection was detected.Etching rates, as judged by the occurrence of matte spots, were least when the beam was parallel to the close‐packed [110] directions and greatest when parallel to high index directions making large angles with the [110] directions. Low etching rates were also observed when the beam became parallel to [100] and [112] directions. Any anisotropy in surface migration rates was shown to be negligible in controlling etching rates under the conditions of these experiments.

ISSN:0021-8979    

DOI:10.1063/1.1729578

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

By diffusing copper into the surface of conductive cadmium sulfide single‐crystal samples, thin piezo‐electrically active layers have been formed. Such diffusion layers have been shown to act as ultrasonic transducers with operating frequencies well above 100 Mc. Short delay lines with less than 30 dB of insertion loss at 175 Mc have been made using such diffusion layer transducers.

ISSN:0021-8979    

DOI:10.1063/1.1729579

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The effective electrical conductivity &sgr; is computed for a composite medium consisting of a dense cubic array of identical, perfectly conducting spheres imbedded in a medium of conductivity &sgr;0. Whenf, the fractional volume occupied by the spheres, is near its maximum value &pgr;/6, the result is&sgr;/&sgr;0=−(&pgr;/2)log[(&pgr;/6)−f]+…,(&pgr;/6)−f≪1.This result exhibits the singularity of &sgr; atf=&pgr;/6, when the spheres touch each other. The previous results of Maxwell, of Rayleigh and of Meredith and Tobias are not valid near the singularity and they fail to reveal it. Forf=0.5161 our result yields &sgr;/&sgr;0=7.65, while the measurement of Meredith and Tobias yielded &sgr;/&sgr;0=7.6.For a medium containing a square array of perfectly conducting circular cylinders we obtain&sgr;/&sgr;0=&pgr;32/2[(&pgr;/4−f)]12+…,(&pgr;/4)−f≪1.This result agrees well with the numerical results of H. B. Keller and D. Sachs. We also prove that for any value off, &sgr;/&sgr;0for a medium containing a square array of nonconducting cylinders is the reciprocal of &sgr;/&sgr;0for the same array of perfectly conducting cylinders.

ISSN:0021-8979    

DOI:10.1063/1.1729580

出版商:AIP    

年代:1963

数据来源: AIP