摘要:

A theoretical technique is described for determining the melting line for solids with a linearUs−up(i.e., shock velocity‐particle velocity) relationship, utilizing the Lindeman law and an accurate Gru¨neisen equation of state. A theoretical melting curve for copper is presented, and its good agreement with static high‐pressure measurements is noteworthy in view of recent criticism of the Lindemann law.

ISSN:0003-6951    

DOI:10.1063/1.1654412

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Calculations show that a soft x‐ray laser is feasible when a solid target of low atomic number is excited with a focused mode‐locked Nd: glass laser of power level≳ 1012 W. Quantitative evaluation of the physical processes involved, such as ionization, inversion, stimulated emission, and Auger effect, is presented.

ISSN:0003-6951    

DOI:10.1063/1.1654413

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

It is shown that interference between incident and reflected light waves at the surfaces of a transparent dielectric material significantly influences surface damage thresholds. For normal incidence the light that is reflected at the entrance face of a surface is 180° out of phase with the incident light, and the resulting interference causes a sizable reduction in the electric field at the entrance face. The light reflected at the exit face suffers no phase shift, and as a result its interference with the incident light slightly increases the electric fields experienced at the exit surface. The analysis predicts a definite ratio for the damage threshold of the entrance and exit surfaces. This and one other prediction are experimentally investigated for Owens‐Illinois ED‐2 laser glass.

ISSN:0003-6951    

DOI:10.1063/1.1654414

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The conventional dynamical equations of wall motion are modified by a phenomenological nonlinear damping factor to describe the nonlinearity and velocity saturation observed in some bubble materials. We show that under certain restrictive but common conditions the solution of the resultant nonlinear differential equation can be obtained from the conventional linear solution by the simple transformationt→t±x/v, wherevis the saturation velocity. The conditions for this solution are (a) that the inertial terms are negligible and (b) that the motion is such that the velocity does not change sign. Solutions of the modified dynamical equation are compared with measurements of step‐function wall response and of bubble collapse in Y2.4Eu0.6Fe3.8Ga1.2O12, and it is shown that the measurements are consistently and adequately described by the nonlinear dynamical equation. The nonlinear damping also modifies the equation describing bubble velocity in gradient fields, and it is shown that the modified equation is consistent with propagation data.

ISSN:0003-6951    

DOI:10.1063/1.1654415

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Time‐average optical holographic interferometry techniques have been used to obtain measurements of an array of sonar transducer elements operating underwater in a 15‐m‐diam 30‐m‐deep tank. Holograms were made from outside the tank through a pair of portholes using an argon‐ion laser. Measurements were made to provide experimental verification of predicted acoustically induced mutual coupling effects. The quality of the hologram reconstructions was sufficient to resolve fringes spaced 1 mm apart from a viewing distance of 7.5 m.

ISSN:0003-6951    

DOI:10.1063/1.1654416

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Electron injection has been accomplished in a thick (10–20 mil) ordered insulator (single‐crystal sapphire), using an internal photoemission technique. It is shown that transport properties of electrons in ordered insulators can be easily measured using this technique.

ISSN:0003-6951    

DOI:10.1063/1.1654417

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Experimental results on the convolution of surface waves in a structure of CdS‐water‐LiNbO3are reported. The convolved output has been enhanced by applying a dc electric field across CdS having the proper conductivity. The enhancement is large enough to offset the losses involved producing a net electronic gain for the convolution process.

ISSN:0003-6951    

DOI:10.1063/1.1654418

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A method is presented of measuring the pyroelectric coefficient &lgr; and permittivity &egr; from the initial slope, rise time, and peak value of the pyroelectric response to step radiation signals, valid for temperatures up to the Curie point. An experiment carried out on single‐crystalline triglycine sulphate has yielded the temperature dependence of &lgr; and &egr; with reasonable accuracy and in good agreement with other methods.

ISSN:0003-6951    

DOI:10.1063/1.1654419

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed.

ISSN:0003-6951    

DOI:10.1063/1.1654420

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Heterojunction solar cells consisting ofpGa1−xAlxAs&sngbnd;pGaAs&sngbnd;nGaAs are grown by liquid‐phase epitaxy and exhibit power conversion efficiencies of over 16% (corrected for contact area) measured in sunlight for air mass 1 at sea level, while efficiencies of 19–20% are obtained for an air mass value of 2 or more. The improved efficiencies compared to conventional homojunction (Si and GaAs) cells are attributed to the reduction of series resistance and the reduction of surface recombination losses resulting from the presence of the heavily doped Ga1−xAlxAs layer. Open‐circuit voltages of 0.98–1.0 V and short‐circuit currents of 18–21 mA/cm2(corrected for contact area) are observed for a solar input intensity of 98.3 mW/cm2.

ISSN:0003-6951    

DOI:10.1063/1.1654421

出版商:AIP    

年代:1972

数据来源: AIP