摘要:

A systematic procedure is developed for finding analytical solutions of certain ordinary linear differential equations of arbitrary order, describing reflection and conversion of waves in multiwave media having a concentrated region of nonuniformity. This procedure involves transformation to equations solvable by generalized hypergeometric functions which have the form of normal modes, exp(−ikz), in uniform regions. It is applicable when the variable coefficients in the original equation contain only linear combinations of one varying parameter,p(z), and in certain cases its derivatives or ratios thereof, ifp(z) is proportional to tanhz. Arbitrary gradients and dissipation are allowed. The applicability of this procedure to solve for the reflection and conversion coefficients is indicated for second‐, fourth‐, and sixth‐order problems in magnetostatic, spin, and elastic‐wave conversion in magnetic insulators such as yttrium iron garnet, and for electromagnetic‐to‐electrostatic wave conversion in hot plasmas. Some of these problems involve fourth‐order singular turning points formed by the coalescence of resonance and cutoff. Explicit expressions for the reflection and conversion coefficients are given for fourth‐order systems in terms of &Ggr; functions of complex arguments. In the absence of dissipation, the absolute magnitude of these coefficients may be expressed in terms of ordinary transcendental functions.

ISSN:0021-8979    

DOI:10.1063/1.1663660

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Starting with highly purified feed material, single crystals of semiinsulating CdTe were grown by the use of the traveling heater method, without external chemical compensation. Evaluation of the crystals by the use of electrical and optical measurements showed decisive improvements in quality. Nuclear radiation detectors prepared by the use of this material resulted in an energy resolution (FWHM), at room temperature, of 4.6 and 8.5 keV for &ggr; rays at energies of 122 and 662 keV, respectively. The energy resolution at 122 keV decreased to 3.8 keV at a temperature of −30°C. No polarization effect was observed.

ISSN:0021-8979    

DOI:10.1063/1.1663661

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The refractive index of GaAs0.62P0.38has been determined from double‐beam reflectance measurements. Near the peak emission energy of GaAs0.62P0.38light‐emitting diodes, the refractive index is 3.68.

ISSN:0021-8979    

DOI:10.1063/1.1663662

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

With the aid of elementary beam theory a Lagrangian equation of motion was developed to relate the crack velocity to cleavage energy in a double‐cantilevered single‐crystal specimen when shear contributes significantly to the cleavage energy. For a constant cleavage energy the equation predicts that the square of crack length is proportional to time when the crack is long with respect to transverse specimen dimensions. For shorter cracks, crack length is proportional to time.

ISSN:0021-8979    

DOI:10.1063/1.1663663

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Magnesium fluoride laser emission has been produced from the chemical reaction of explosively generated magnesium jets and fluorine. The temporal and spectral characteristics of these laser pulses are similar to those reported earlier for the MgF exploding wire laser, i.e., pulse duration of 1–3 &mgr;s, and wavelength > 11&mgr;m, which suggests a purely chemical pumping mechanism for both of these metal atom oxidation lasers.

ISSN:0021-8979    

DOI:10.1063/1.1663664

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Tunneling between lead‐gold layered films separated by an oxide barrier has been investigated. From these results, the superconducting transition temperature and the energy gap of the compound, AuPb3, present in these films have been deduced.

ISSN:0021-8979    

DOI:10.1063/1.1663665

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The temperature behavior of minority‐carrier lifetimes was measured in undopedn‐type and Cd‐dopedp‐type GaAs single crystals. The results were explained on the basis of a model for the recombination mechanism using one type of minority‐carrier trapping centers and one type of recombination centers, the latter having a very small density. Furthermore, the model assumed a gradual transformation of trapping centers to recombination ones with decreasing temperature. The same model also explained the difference between our results on the majority‐carrier lifetime behavior and the results of other investigators on the same subject.

ISSN:0021-8979    

DOI:10.1063/1.1663666

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The composition of thin SiO2films was measuredin situby MeV He+backscattering spectrometry after sequential sputtering with 2‐keV Ar ions. Results indicate that the relative concentration of the constituents in the film changes during sputtering. However, differential analysis showed that after an initial period the ratio of the removed constituents agrees with the original composition. We interpret the change in composition with an existing model according to which only the composition of a thin surface layer changes due to the dissimilar sputtering ratios of the two constituents, while the composition in the remainder of the specimen is unchanged.

ISSN:0021-8979    

DOI:10.1063/1.1663667

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Data on resistivity at room temperature in polycrystalline and single‐crystal Permalloy (80 Ni‐20 Fe) thin films are analyzed in terms of grain boundary scattering and the dc size effect, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1663668

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Electron distributions in a Penning discharge, consisting of two glow discharges separated by a cylindrical microwave cavity with gridded ends, were measured using the shift of resonant microwave frequencies and Langmuir probe data. The shape and magnitude of the distributions were determined for a range of pressure, discharge current, magnetic field, and for several cathode shapes. The microwave technique gives the distribution as a two‐parameter function, and the probe data gives a more detailed profile but quantitatively less reliable. All data indicated that the plasmas were electron rich. The distributions were azimuthally symmetric with a maximum at the center at higher pressures; at lower pressures and higher magnetic fields, the densities were depressed in the center, indicating the development of a circulating sheath of electrons. The data indicates that the microwave diagnostic technique is quite suitable when the distribution is a maximum at the center, and it is a useful procedure for calibrating a probe when there is no suitable probe theory for a particular range of experimental parameters.

ISSN:0021-8979    

DOI:10.1063/1.1663669

出版商:AIP    

年代:1974

数据来源: AIP