摘要:

This paper discusses certain of the noise characteristics of silicon broad area junctions which have been developed for use for solar energy conversion. Under constant illumination the photovoltaic output of these junctions has been found to show fluctuations which are characteristic of a 1/fnoise power spectrum. For varying illumination the magnitude of the photovoltaic noise voltage has been found to vary considerably, and in fact passes through a pronounced maximum. A plausible explanation of this effect is obtained by assuming that fluctuations are produced in the primary photocurrent as a result of traversing the junction. The assumption of a current dependent noise mechanism is justified by an independent experiment.

ISSN:0021-8979    

DOI:10.1063/1.1722196

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Methods for estimating the gamma‐ray dosage in samples undergoing irradiation in nuclear reactors are developed. They are applied to the calculation of the dosage in inhomogeneous reactors using CP‐3 and X‐10 as examples. The examples include a calculation of the heating which results from the absorption of gamma rays and of the chemical reaction which results from the absorption of gamma rays. The non‐uniformity of the gamma‐ray dosage in bodies undergoing irradiation is demonstrated and estimated. The results show that in nuclear reactors the gamma‐ray dosage varies very greatly depending on the experimental arrangements and that, in particular cases, the major contribution to the dosage can arise from any of the following individual sources or some combination of them: the material being irradiated, the containers, the structural members of the irradiation facility, the moderator, or the fuel.

ISSN:0021-8979    

DOI:10.1063/1.1722197

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Experimental measurements of jet velocity and of penetration velocity as functions of depth of penetration are described for lined cavity charges fired into several types of target material and under a variety of experimental conditions. The results show that the hydrodynamic theory of penetration of Pugh and of Hill, Mott, and Pack describes very accurately the early stages of the penetration process. Strength of the target becomes an appreciable factor in the later stages, however. A simple modification of the theory is described which appears to account adequately for these strength effects. Some alterations in ideas concerning the mechanism of penetration by the jet after fracture are also described.

ISSN:0021-8979    

DOI:10.1063/1.1722198

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

It is proposed that the discontinuity is a manifestation of the sudden change in the expansion coefficient that occurs at the glass‐transition temperature. A comparison of volume‐temperature data with velocity‐temperature and velocity‐pressure data taken from the literature gives reasonably good agreement with this explanation. Further, the dependence of velocity on density is seen to be chiefly through the strong dependence of the modulus on density and to a lesser extent through the appearance of density explicitly in the equation that relates velocity to the density and modulus.

ISSN:0021-8979    

DOI:10.1063/1.1722199

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The primary objective of this study was to determine the effects of geometric parameters on microwave transmission characteristics for two counter‐rotating circularly polarized waves in ferrite loaded wave guide. Ferrite rods were mounted coaxially in circular wave guide of 0.934 in. diameter. Effects of rod diameter and length were observed on reflection, phase shift or Faraday rotation, and ellipticity. Effects of frequency and applied magnetic field were observed in addition to differences in energy concentration in a ferrite for the two circular waves. A greater percentage of the microwave energy is found to be in the ferrite for one rotating component than for the other. It is shown that Faraday rotation of large diameter rods cannot be used to characterize ferrites accurately.

ISSN:0021-8979    

DOI:10.1063/1.1722200

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A dynamic method has been developed for the study of the pyroelectric effect. Transient currents produced in single crystals of barium titanate when subjected to flashes of light are shown to be pyroelectric in origin. The illumination results in a small change in the temperature of the crystal which, in turn, causes the polarization to change. This change is recorded as a current in the external circuit. It is shown that from room temperature up to the Curie point, the pyroelectric current is consistent with the polarization as a function of temperature, as determined from hysteresis loop measurements. The technique proves to be a sensitive and nondestructive method for studying the state of polarization of a crystal.The technique is used to study the pyroelectric effect induced by applied static electric fields at temperatures above the Curie point. The results are consistent with Devonshire's theory of the ferroelectricity of BaTiO3, and they confirm that the Curie point transition is of the first order.

ISSN:0021-8979    

DOI:10.1063/1.1722201

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Magnetic torque measurements and electron diffraction patterns on several cobalt ferrite and cobalt‐zinc ferrite crystals show that those compositions which respond to heat treatment in a magnetic field contain precipitated particles of a second phase. Response of these crystals to heat treatment in a magnetic field is apparently due to the tendency of the precipitated particles to grow preferentially along the field direction in a manner similar to that previously reported by Heidenreich and Nesbitt [J. Appl. Phys.23, 352 (1952)] for Alnico 5. When the crystals are heat treated without a magnetic field the precipitated particles are oriented along the crystal axes, and the shape anisotropy of the particles arrayed in this manner causes a reversal in sign of the torque as the measuring field is increased from zero. This anomalous variation of the torque with field was previously observed with Fe2NiAl and explained on the same basis. Thus a single mechanism explains the aforementioned magnetic phenomena observed in Fe2NiAl, Alnico 5, and the cobalt ferrites.

ISSN:0021-8979    

DOI:10.1063/1.1722202

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The spatial distribution of thermal neutrons originating from a fast neutron line source, with slowing down described by age theory, and thermal percolation through an infinite, isotropic medium described by diffusion theory, is presented.

ISSN:0021-8979    

DOI:10.1063/1.1722204

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A siliconp‐njunction photocell prepared by the gaseous diffusion process and biased in reverse showed no noise in excess of shot noise down to a frequency of 80 cycles per second in a dry atmosphere. In a humid atmosphere the excess noise was a factor of 3×105above shot noise at 100 cycles and showed the familiar 1/fspectrum.

ISSN:0021-8979    

DOI:10.1063/1.1722205

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722207

出版商:AIP    

年代:1956

数据来源: AIP