摘要:

This paper extends the study of resonance rectification phenomena in plasmas to the case where a static magnetic field is present. Parallel wire‐probe geometry has been chosen so that the rf electric field is primarily perpendicular to the magnetic field. Under these conditions, experiments show that there are two distinct series of resonance peaks, one occurring between successive cyclotron harmonics, the other precisely at the cyclotron harmonics. Cold‐plasma theory is inadequate to account for the existence of these resonances. An explanation is proposed, based on the form of the warm‐plasma permittivity component perpendicular to the magnetic field, which explains satisfactorily all of the experimental observations.

ISSN:0021-8979    

DOI:10.1063/1.1709278

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

TheR‐line fluorescence in ruby was excited with the nanosecond light pulses, and the slope of the rise curve was studied as a function of the pulse width at room temperature. The purpose of the experiment was to determine the value or the upper limit of the nonradiative relaxation time between the pump bands4T1, 2and the fluorescence state2E. The upper limit of 5 nsec was determined. A brief review of previous work is given.

ISSN:0021-8979    

DOI:10.1063/1.1709279

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The Hall coefficient, temperature coefficient of resistance, and conductivity of Cr‐SiO cermet films were measured as a function of film composition. The behavior of the Hall coefficient indicates this material should be treated as a two‐carrier system. A model is proposed which may account for this behavior and for the dependence of the temperature coefficient of resistance on small concentrations of SiO.

ISSN:0021-8979    

DOI:10.1063/1.1709280

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The light emission from reverse‐biased GaAsp‐njunctions was investigated using current pulses. Appreciable light emission was obtained only in the breakdown range. Light‐emission waveform had three components, i.e., emission waveform of nearly the same shape of current pulse (first component), emission wave delaying about 2 &mgr;sec from the onset of current pulse (second component), and unstable emission peak near the last part of the current pulse (third component). For the first component, the position of the reverse‐biased emission was the same as that of the forward‐biased emission. The light of the second component was emitted fromn‐type region of the diode, and this component will occur from the saturation of recombination rate near the junction. The third component was emitted from the relatively wide range of then‐type region containingp‐njunction, and this emission peak is the phenomenon preceding the destruction of the diodes.

ISSN:0021-8979    

DOI:10.1063/1.1709281

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The theory of the magnetic‐field dependence of the Hall coefficient in a simple, multiband model is reviewed. The complete expression rapidly becomes more complicated as the number of bands increases. Simple limiting forms, valid for any number of bands, have been derived earlier for weak magnetic fields, and for the high‐field limit when there is no compensation (i.e., when the electron and hole concentrations arenotequal). It is shown that a simple result also occurs in the high‐field limit,withcompensation, for any number of bands.

ISSN:0021-8979    

DOI:10.1063/1.1709282

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The Ginzburg‐Landau equations are solved for thin superconductors in the presence of arbitrary tangential magnetic fields and yield an essentially position‐independent order parameter if the superconductor contains no vortices. The magnetic transition is always first order unless the field is symmetrical on the surface; if the field comes from a superposition of external source and transport current, the critical order parameter &PHgr;cis a one‐third power function of the current. It is shown that the physical conditions for the above solution can be realized with a superconducting transmission line, and that the order parameter is directly measurable in terms of the resonant frequency of the line. The measurements made on tin samples at temperatures down to 0.6Tcshow excellent agreement with the theory, and constitute an experimental vertification of the latter.

ISSN:0021-8979    

DOI:10.1063/1.1709283

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

This paper demonstrates that, for a given crystalline solid, the first pressure derivatives of polycrystalline elastic moduli can be predicted either from the corresponding derivatives of anisotropic single‐crystal elastic constants or from their single‐crystal third‐order elastic constants. Theoretical relations for the isotropic polycrystalline acoustic data in terms of their single‐crystal acoustic data are presented here for cubic, hexagonal, trigonal, and tetragonal crystals; these have been successfully applied for four cubic solids (Al, Cu, &agr;‐Fe, and MgO) and one hexagonal metal (Mg). It is shown for these solids that the calculated isotropic acoustic data agree essentially with experimental acoustic data determined on their polycrystalline specimens, thus establishing the validity of the theoretical relations. It is concluded that the acoustic data measured onfully densepolycrystalline specimens may be as useful as the single‐crystal acoustic data in the study of the equation of state of solids, for example. And further, when anisotropic single‐crystal acoustic data are available, these can be converted into isotropic polycrystalline acoustic data so that in their applications, the use of the acoustic data becomes more practical.

ISSN:0021-8979    

DOI:10.1063/1.1709284

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The widths and positions of several lines in the fluorescence spectrum of ruby with 0.94 at.% Cr3+belonging to the second (N1) and the fourth (N2) nearest neighbor pair systems have been measured between 20° and 270°K. The linewidths are explained in terms of microscopic strains, Raman scattering of phonons, and direct phonon processes. The lineshifts with temperature are due to the absorption and emission of virtual phonons, and are approximately the same for all the lines investigated. A Debye model of phonons was used with different effective Debye temperatures for linewidth and lineshift processes.

ISSN:0021-8979    

DOI:10.1063/1.1709285

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Superconducting indium films are studied to determine the effect of film thickness on transition temperature in the range of thicknesses from about 100 to about 1000 A. Films of varying thicknesses are produced by vacuum deposition ontoz‐cut quartz substrates. To ensure reproducibility, films are produced in groups of five. Comparisons are made with the theoretical models of Toxen and Stronginet al., and the effect of electron mean free path is calculated in an approximate manner. In addition, an effective electron‐phonon coupling constant is obtained for the surface‐layer model.

ISSN:0021-8979    

DOI:10.1063/1.1709286

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The temperature increase in vacuum‐evaporated films of Au and Ag was measured by allowing the evaporant to condense on the junctions of Au‐Ni thin‐film thermocouples connected in series. The (minimum) average film temperature during growth was found to depend upon the evaporation rate and the substrate temperature. The average temperature of thin films of Au and Ag during deposition can be some 400°–500°K higher than the substrate temperature; this increase is attributed to the exothermic heat of condensation and radiation heating from the evaporation source. Even at low substrate temperatures near 100°K, the average film temperature can approach 500°K. The significant temperature existing in evaporated thin films can explain grain growth phenomena and other metallurgical changes in the structure of the films.

ISSN:0021-8979    

DOI:10.1063/1.1709287

出版商:AIP    

年代:1967

数据来源: AIP