摘要:

This paper presents mathematical formulations for new, three‐dimensional, packet‐like solutions to the free‐space homogeneous Maxwell’s equations. These solutions are real, nonsingular, continuous functions which propagate in a straight line at light velocity. They remain focused for all time. The asymptotic behavior of the fields away from the moving pulse center has a magnitude which decreases as the inverse of the distance from the pulse centers.

ISSN:0021-8979    

DOI:10.1063/1.332196

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

It is shown that the stationary fluctuations described by the diffusion equation of an effective space dimension less than one have a 1/fspectrum. A physical diffusion model equivalent to such a low dimensional diffusion process is proposed. Here, a singular disturbance of temperature fluctuation is assumed to diffuse with the space‐dependent diffusion coefficientD(r)=D0(1+&kgr;r−m)&thgr;. Here,D0is the constant part of the diffusion coefficient and &kgr;r−mrepresents the effect of local temperature enhancement of the background medium caused by the singular disturbance itself, whereris the distance from the singular disturbance atr=0, andmand &thgr; positive constants.

ISSN:0021-8979    

DOI:10.1063/1.332197

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A response function method using externally applied random force is developed to identify linear or nonlinear systems. The probability distribution function of fluctuations and probability flow in phase space are used as the means for these identifications. It is also demonstrated that anomalous behavior of these quantities can be utilized as the forerunner phenomenon of the catastrophe of unstable systems.

ISSN:0021-8979    

DOI:10.1063/1.332198

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A high‐temperature optical fiber thermometer made from single crystal sapphire has been developed for use from 600 to approximately 2000 °C. The device consists of a small blackbody cavity which is sputtered on the end of a thin (0.25–1.25‐mm diameter, 0.05–0.30‐m length) sapphire fiber, a connecting low‐temperature glass fiber, and a conventional optical detector. The radiance from the cavity is used to measure its temperature. The present instrument is calibrated at a single temperature and uses the fundamental radiation laws to extrapolate to other temperatures. It is accurate and has a high sensitivity and rapid temporal response. There appear to be a number of applications of the device both in science and industry.

ISSN:0021-8979    

DOI:10.1063/1.332199

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Thick target yields ofL&agr; x rays (x rays/str electron) under electron bombardments from around threshold energy to 30 keV are presented for pure elements of Sn, Sm, Ta, W, Pt, Au, and Pb. The calculation ofKx‐ray yields by Green and Cosslett has been applied to the deduction ofL&agr; x‐ray yields and observed data have been compared with the calculation. A good agreement has been obtained for highZelements. An empirical formula for observedL&agr; x‐ray yieldsIL&agr;(x rays/str electron) has been found to be expressed byIL&agr;=1.3×10−7×Z1.3(UL3−1)1.46×0.938[ln(UL3−1)]2in impact energies less than 30 keV, whereUL3is the overvoltage ratio defined by the ratio of electron impact energy toL3shell ionization energy.

ISSN:0021-8979    

DOI:10.1063/1.332200

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Fusion reactivities ⟨&sgr;v⟩ in the mean ion energy range 0.1–200 keV have been calculated for the reactions: D(d,n), T(d,n), D(d, p),3He(d, p) and T(t,2n); and for several different ion energy and angular distributions considered plausible in hot, magnetically confined plasmas. Calculations were carried out to a numerical accuracy of about 5% and the resulting variation of reactivity with mean ion energy is found to be well represented by a simple polynomial function. The polynomial functions are plotted as a function of mean ion energy and their coefficients given. Results of the calculations show that fusion reactivity is very sensitive to the functional form of the speed distribution at mean energies below a few keV, but reactivity is roughly independent of the form of the speed distribution (within a factor of 2) above 10 keV for most of the reactions investigated. Similarly, the importance of the ion angular distribution is large at energies below a few keV but small at high ion energies.

ISSN:0021-8979    

DOI:10.1063/1.332201

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

XeF2was reacted with silicon, and the gaseous products were detected using modulation techniques which made the experiments sensitive only to products which had not collided with a wall. In agreement with previous experiments, SiF4was found to be the major reaction product. Radicals such as SiF and SiF2were observed at a much lower level. However, SiF2was not found to be the dominant species as might have been suspected on the basis of experiments by other workers with atomic fluorine. Bombardment with 2000‐eV argon ions enhanced the rate of product formation and decreased the fraction of the products that was SiF4. Production of radical species, in particular SiF2, was enhanced. Collisions of SiF2with fluorinated, stainless‐steel vacuum chamber walls were investigated in order to determine whether the SiF2radical was converted to SiF4as suggested by others. Wall reactions were found to be important in some circumstances and not important in others.

ISSN:0021-8979    

DOI:10.1063/1.332202

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Inductively stabilized discharges are developed for the rare‐gas halide minilasers. 6.8 mJ per pulse with 40‐ns full width at half‐maximum pulse lengths and 3.7 mJ per pulse with 60‐ns full width at half‐maximum pulse lengths are obtained for KrF. 3.1 mJ per pulse with 40‐ns full width at half‐maximum pulse lengths and 1.7 mJ per pulse with 60‐ns full width at half‐maximum pulse lengths are obtained in XeCl. The discharge dimensions are 2.5‐mm electrode separation by 4 mm wide and 27.6 cm long. Orders of magnitude increases in pulse repetition frequency are obtained in devices that do not utilize gas flow.

ISSN:0021-8979    

DOI:10.1063/1.332203

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Performance characteristics are reported for a transverse‐flow, oxygen‐iodine chemical laser which operates at a low level (8 m/s) of linear flow gas velocity using a small size vacuum pump. This is the first time that dependences of laser output power have experimentally been found on Cl2and I2flow rates. Output powers in excess of 10 W have been efficiently extracted from a 50×0.5‐cm rectangular flow duct. A total energy of 11 kJ from one gram of iodine has been obtained. The reaction mechanisms associated with the power decrease in high concentrations of I2are carefully discussed.

ISSN:0021-8979    

DOI:10.1063/1.332183

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Long lived, lifetested GaAlAs/GaAs stripe geometry, double heterostructure lasers have been examined in the scanning electron microscope using a combination of cathodoluminescence, electron beam induced conductivity, and electron probe microanalysis. The dark spot arrays, occasionally seen in the cathodoluminescence images of the active layers of these devices, have been found to be caused by the diffusion of copper into the laser chip from the heat sinks, despite the presence of a nickel barrier layer on the heat sinks.

ISSN:0021-8979    

DOI:10.1063/1.332184

出版商:AIP    

年代:1983

数据来源: AIP