摘要:

The spectrum of power radiated by a solid‐state optical maser in steady‐state operation is obtained by considering each atomic system to be a source of randomly fluctuating dipole moment which drives every mode of the cavity. The nonlinear behavior of the collection of atomic systems is treated in such a way that a detailed examination of the distribution of power in the various modes is possible. A number of examples are considered which show how critically dependent on the relative loss rates of the various modes are the characteristics of the output from a multimode oscillator. An interesting result of this calculation is the appearance in some cases of an abrupt transition as the pumping power is increased: above this point a large fraction of energy goes into the mode which is resonant with the atomic transition and which has the lowest loss rate. Another case is studied which does not have this feature, but which could be useful in analyzing the behavior of solid‐state optical masers which have substantial scattering due to crystal imperfections.

ISSN:0021-8979    

DOI:10.1063/1.1736202

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Serious limitations are encountered in the analysis of insulators when conducting tubes packed with the powdered insulator are the electrodes of the vacuum spark. A general method of forming a vacuum spark directly between a conductor and a slab of insulator, which removes the above limitations, is presented. Mass spectral data of the insulators steatite and quartz are presented showing the presence of bulk impurities and surface contamination.

ISSN:0021-8979    

DOI:10.1063/1.1736203

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The mass spectrograph with the vacuum spark positive ion source distinguishes between bulk impurities in the electrodes and contaminants present on their surface. Surface contamination can be detected and identified when it is the equivalent of less than 0.01 monolayer in thickness. Impurities in liquids are studied by exposing an electrode to the liquid, thereby contaminating its surface. Two ways of contaminating an electrode surface are described: (a) electroplating of impurities onto the electrode, and (b) evaporation leaving residue on the electrode. Experiments with doped water demonstrate that impurities at a concentration of 10−9atom fraction can be detected. Only about 10−10g of impurity is needed for detection using the evaporation technique. Some applications are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1736204

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The excess current in silicon Esaki diodes has been shown to be a sensitive indicator of the density and distribution of states intorduced into the forbidden gap by electron bombardment. Both the effects of bombardment and the annealing properties of the radiation damage have been found to depend upon the specific donor in then‐type region of the diode. The average bombardment dose of 1‐Mev electron/cm2needed to increase the excess current density by 1 amp/cm2at a bias of 0.3 v is 1.2×1016for P‐doped diodes and 0.8×1016for Sb‐ or As‐doped diodes. Upon annealing in an inert atmosphere, at temperature in the range 300°–400°C, the bombarded diode is restored to its original characteristics. While the annealing studies reveal novel interactions, they show considerable similarity with other work where the radiation damage was monitored by carrier lifetime or conductivity measurements. Structures observed in the I–V characteristics during the annealing indicate that the bombardment‐induced levels atEv+0.27 andEv+0.06 are due to pairing of a primary defect (probably a vacancy) with an arsenic and a phosphorus impurity atom, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1736205

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Two phenomenological models are considered by which impulsive random noises can be described: (a)Poisson noise, consisting of the superposition of independent, randomly occurring elementary impulses. Much electronic noise belongs to this type and the familiar physical examples are precipitation noise, ignition noise, and solar ``static.'' (b)Poisson‐Poisson noise, consisting of the superposition of independent, randomly occurring Poisson noise, each type of Poisson noise forming a wave packet of some duration. Atmospheric noise is a representative example of the latter type. The attempt at first is made to deduce the general amplitude distribution for each model; then, because the noise sources in nature are spatially distributed and noise strength decreases with distance so that the amplitude of the received noise sometimes depends seriously on this spatial distribution of noise sources, the amplitude probability distributions are considered according to the two typical cases of the discrete and continuous spatial distributions, and are compared with those of actual atmospherics. Moments of even order and correlation functions are also calculated for each model. Finally, the dependence of the assumptions used on amplitude probability distribution are discussed. The distributions obtained are, in some cases, found to be independent of the adopted models and some of the used assumptions in a wide range of noise amplitude.

ISSN:0021-8979    

DOI:10.1063/1.1736206

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

High‐purity zinc crystals were grown from the melt by the soft mold technique, and bent in such a way that [01¯10] was parallel to the bending axis and the [211¯0] slip direction enclosed approximately 45° with the bending radius. A dislocation etching technique was developed, which reveals the edge dislocations introduced on bending, without the necessity of decoration. It was found that crystals bent either at room temperature or at liquid nitrogen temperature had approximately two‐thirds of the edge dislocations arranged in low‐angle tilt boundary segments. The fact that no observable change occurred in the dislocation structure on annealing up to 225°C for 5000 min suggests that the observed low‐angle boundaries were formed directly on bending rather than by a thermally activated polygonization process, which might have been thought to take place at room temperature in the interval between bending and etching.

ISSN:0021-8979    

DOI:10.1063/1.1736207

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Dielectric dispersion measurements have been carried out on barium titanate single crystals of different thicknesses at temperatures above the Curie point ranging up to 180°C. In the high‐frequency range of the measurements (100 kc), the measured dielectric constant of thin crystals is consistently much smaller than that of thick samples. The effect is ascribed to the presence of a layer of low dielectric constant on the surface of the crystals, with a capacitance of the order of 0.5 &mgr;f/cm2in the temperature range explored. The relaxation time of this surface layer is found to be at least 10−4sec at 120°C on crystals which have not been ``aged'' recently.

ISSN:0021-8979    

DOI:10.1063/1.1736208

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The model proposed by Gatos and Lavine [H. C. Gatos and M. C. Lavine, J. Electrochem. Soc.107, 427 (1960)] for the dangling bonds of III–V compounds is discussed in the context of the available experimental facts and the objection advanced by Holt [D. B. Holt, J. Appl. Phys.31, 2231 (1960)]. It is shown that the model as originally proposed is consistent with basic principles and experimental observations.

ISSN:0021-8979    

DOI:10.1063/1.1736209

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A microscopic Faraday effect apparatus is described by means of which the fine structure of the domain configurations in thin Permalloy films has been observed. The direction of the magnetization in cross‐tie domain walls and other domain configurations has been deduced from their light, dark, or gray appearance and known polarizer angles. Faraday effect hysteresis loops are presented in support of a proposal that domain walls at 45° to the easy direction represent an intermediate demagnetized state in films having a high degree of uniaxial anisotropy.

ISSN:0021-8979    

DOI:10.1063/1.1736210

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Previous work by other investigators has shown that a sharply cusped minimum occurs in the resistivity‐temperature relationship for fully recrystallized chromium at the Ne´el temperature, i.e., 35°C. Plastic deformation, on the other hand, eliminates this minimum, and in addition gives rise to a pronounced change in the resistivity‐temperature relationship over a wide range of temperatures centered about the Ne´el temperature. These results have been corroborated in the present paper. Furthermore, this behavior has been analyzed and interpreted in terms of the strong dependence of the Ne´el temperature on hydrostatic stresses which are thought to arise from the presence of dislocations in the deformed material.

ISSN:0021-8979    

DOI:10.1063/1.1736211

出版商:AIP    

年代:1961

数据来源: AIP