摘要:

The ion optical properties of an azimuthally invariant magnetic field which are important in the electro‐magnetic separation of isotopes are considered. The solutions are limited to the case where the object and image are within the field. A method based on the principle of least action is used to find general expressions for the values of the coefficients in the field expansion that will produce midplane focus at any angle. The three‐dimensional motion of ions is considered with regard to isotope separations, and the general focal properties of inhomogeneous magnetic fields that satisfy the midplane image requirements are described.

ISSN:0021-8979    

DOI:10.1063/1.1713931

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Electron and optical microscopy were applied in studying laser‐irradiated metal surfaces. The preparation of carbon replica films of irradiated surfaces is described. A summary of observations from irradiated Ag, Al, Be, Cu, Pb, and low‐carbon steel is given. Microcraters of less than 10 &mgr; diam were found to be an early stage in the development of radiation damage on laser‐irradiated metal surfaces. The observed surface structure is assumed to be of interest when interpreting experiments on the interaction of laser beams with metal surfaces.

ISSN:0021-8979    

DOI:10.1063/1.1713932

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The observed linewidths of the magnetostatic modes of roughened spheres of yttrium iron garnet do not follow the expected simple dependence on the density of degenerate spinwave states. A theoretical explanation is presented of the apparently erratic differences between the linewidths of the low‐order magnetostatic modes. Semiclassical spinwave theory is used to calculate the coupling between the resonant mode and the degenerate spinwaves. Linewidths dependent on surface condition are calculated on the basis of typical values for the parameters to describe rough surfaces, and fit to experimental linewdiths. The calculated and observed linewidths are presented; the agreement between them is very good. The results are consistent with the general assumptions of the previous treatments, but in addition it is shown that it is necessary to include the field configuration of the magnetostatic modes in the calculation of surface‐dependent linewidths.

ISSN:0021-8979    

DOI:10.1063/1.1713933

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A theoretical study is conducted of plane‐harmonic narrow‐band pulse propagation in a statistically uniform but anisotropic transmission medium of weak, stationary refractive‐index fluctuation. Large‐scale inhomogeneities of arbitrary ellipsoidal shape are treated, with transmitter‐to‐receiver ranges taken as large compared with the longitudinal correlation length. Of interest is the influence of range, transmitter frequency, and degree of anisotropy on the pulse shape and intensity. Comparison is made between pulse transmission in isotropic and anisotropic random media, and special attention is given the low‐ and high‐frequency limits of the theory as well as certain extreme conditions of anisotropy. The general formulation is applied to the analysis of both an initially Gaussian and an initially rectangular pulse.

ISSN:0021-8979    

DOI:10.1063/1.1713934

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Measurements of the electric field dependence of the hole diffusion constant inn‐type germanium were made up to 2000 V/cm at temperatures of 297°, 195°, and 77°K. A distinctive feature of our experiments was the attenuation‐rate measurements of sinusoidally modulated hole wave drifting along a filamentary specimen by the electric field supplied from a high‐voltage pulser. The resistivity of the specimen was 5.3 &OHgr;· cm and the hole diffusion constant was obtained which increased nearly in proportion to the two‐thirds power of the electric field above 50 V/cm at 297°K and increased more rapidly at lower temperatures. For example, the result wasDp=900 cm2/sec when the electric field intensity was 1000 V/cm at 297°K.

ISSN:0021-8979    

DOI:10.1063/1.1713935

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A generalized theory of the dependence of the elastic constantC′of heavily dopedp‐type Si on hole concentration is presented. The strain dependence of the valence subband shifts is assumed to be an admixture of terms linear and quadratic in the strain. The theory accounts for the measured values of &dgr;C′=C′doped−C′pureand it is consistent with a constant value of the shear deformation potential constant&Xgr;s′. This is an improvement over previous results, based on purely linear subband shifts in strain, where the interpretation of the experimental data required the assumption of a hole‐concentration‐dependent deformation‐potential constant.

ISSN:0021-8979    

DOI:10.1063/1.1713936

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The Weinreich relation between the acoustic absorption coefficient and the acoustoelectric field in semi‐conductors is found to be modified by carrier trapping. In the presence of dc fields, the acoustoelectric field and the absorption coefficient pass through zero at different values of drift field. The effects of the trapping are particularly important when the trapping time is of the same order as the acoustic‐wave period. The experimental evidence indicates that the above explanation for the effect of trapping is valid, with the dominant traps having a trapping time of about 10−9sec. Some anomalies in the absorption were found which can be explained by the generation of a shear mode which does not interact with the carriers. Nonlinear interactions with this shear mode are found to occur at much lower power levels than those associated with second‐order effects in the theory of Hutson and White.

ISSN:0021-8979    

DOI:10.1063/1.1713937

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Brillouin scattering of light by phonons and the phonon maser are usually described in terms of an approximate set of linearized equations. Here we give a more exact set of equations for a lossless polarizable fluid; only relativistic effects are disregarded. When these equations are linearized and higher order terms in the ratio of sound speed to light speed are disregarded, they reduce to the customary set of equations. The more exact equations permit the derivation of the law of conservation of energy with a simple physical interpretation. From these equations the Manley‐Rowe relations and other conservation laws also follow relatively easily.

ISSN:0021-8979    

DOI:10.1063/1.1713938

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The time dependence of the electron density during the afterglow period of plasma produced in helium‐hydrogen, neon‐hydrogen, and argon‐hydrogen mixtures was measured by means of the microwave cavity method. The time dependence was found to be exponential during the later part of the afterglow period for pressures up to about 25 Torr. The relevant time constant depended on the plasma excitation condition at all values of pressure in helium‐hydrogen mixtures, while this dependence was not observed in neon‐hydrogen mixtures at pressure above 12 Torr and was absent in argon‐hydrogen mixtures. The ion mobility values calculated from the measured ambipolar diffusion coefficients are 38±4 cm2/V·sec for helium‐hydrogen, 17±1.0 cm2/V·sec for neon‐hydrogen and 6.3±0.5 cm2/V·sec for argon‐hydrogen mixtures.

ISSN:0021-8979    

DOI:10.1063/1.1713939

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Departures from the theoretical behavior of a Schottky barrier are reported in the case of gold on gallium arsenide. It is shown that the empirical introduction of a single temperature‐independent parameter takes care of all the observed departures.

ISSN:0021-8979    

DOI:10.1063/1.1713940

出版商:AIP    

年代:1965

数据来源: AIP