摘要:

Backscattering cross sections for depolarization are derived for the active remote sensing of a two‐layer random medium. It is shown that the depolarization effects arise as a second‐order term in albedo under the Born approximation. The results of the backscattering cross sections are illustrated as functions of frequency and incident angles and used to match experimental data collected from a vegetation field.

ISSN:0021-8979    

DOI:10.1063/1.328000

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The propagation characteristics of MSSW in a YIG film are analyzed ray optically considering magnetic field nonuniformity. Significant oscillation of an energy beam is predicted in an ordinary experimental film of thickness 10 &mgr;m. The increase of signal frequency and film thickness makes oscillation stronger, and that of applied field and film width makes it weaker.

ISSN:0021-8979    

DOI:10.1063/1.328001

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The electrostatic field in the development region is mathematically analyzed for a spatially varying image. The effects of space charge due both to charge toner particles and the electrostatic image are included in the field calculation. The results are applied to simple models of xerography and photoactive pigment electrophotography.

ISSN:0021-8979    

DOI:10.1063/1.328002

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Linear accelerators driven by pulse forming networks and utilizing beam neutralization may be useful for obtaining high‐current ion beams for inertial fusion applications. Such accelerators may be subject to longitudinal velocity bunching instabilities. These instabilities are studied with a computer simulation of longitudinal ion dynamics. It is found that they are stabilized by a velocity spread in the beam distribution determined by the properties of the pulselines. The required velocity spread does not preclude obtaining beams of sufficient quality for fusion applications.

ISSN:0021-8979    

DOI:10.1063/1.328003

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Laser emission measurements are reported for thee‐beam excited, near‐atmospheric‐pressure xenon excimer laser. The laser efficiency was limited to the order of 0.1% by the termination of the stimulated emission well before the end of thee‐beam pulse. The premature turnoff was observed under all operating conditions and was not predicted by a modelling code using the same kinetic processes which accurately described fluorescence frome‐beam excited xenon. Broad band transient absorption by the gas medium duringe‐beam excitation was measured. The magnitude of the absorption was less than that predicted for photoionization of the excimers and hence, did not appear large enough to account for the premature turnoff. Temperature increases in mirror coatings due to absorption of the laser radiation and the resulting decrease in mirror reflectivities may account for the observed laser pulse termination.

ISSN:0021-8979    

DOI:10.1063/1.328004

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We have designed and constructed a surface spark discharge UV light source, using a Teflon resin substrate, as a new UV light source for H2/F2laser initiation. The measurements of the time‐integrated spectral characteristics, the radiative UV energy in the region 2700–3900 A, and the lifetime of the surface spark flash in the actual H2/F2laser mixtures are presented. The experimental results have indicated that the surface spark flash using Teflon has a promising performance for practical use in H2/F2laser initiation.

ISSN:0021-8979    

DOI:10.1063/1.328005

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The waveguiding characteristics in a (Al, Ga) As double‐heterostructure laser, where a built‐in refractive‐index profile in the active layer is introduced by impurity concentration profile, have been investigated under the lasing conditions using the planar stripe laser with deep Zn diffusion. The effective refractive‐index step, which determines the waveguiding mechanism, consists of the built‐in refractive‐index step and a negative index step associated with injected electrons into the active region. It has been found that waveguiding characteristics can be changed from antiguiding tendency to normal guiding by varying the combination of hole and electron concentrations.

ISSN:0021-8979    

DOI:10.1063/1.328006

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The possibility of creating population inversions in multiline Mo¨ssbauer nuclei by a two‐stage process, employing neutron capture to generate resonance radiation that then excites states in a separate region, is investigated. Geometrical and kinetic factors and dependences of the interstage coupling on isomer ratios and Mo¨ssbauer parameters are determined. Rate equations for one hypothetical and four actual Mo¨ssbauer isotopes are solved in an approximation that overestimates the excitation; nevertheless, it is found that the necessary neutron capture rates are thermodynamically unattainable.

ISSN:0021-8979    

DOI:10.1063/1.328007

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

This paper presents an investigation on the spatial variation of the average field of a laser beam which is self‐focused in a plasma having random fluctuations in its electron concentration. The analysis is valid for the arbitrary mechanism of self‐focusing nonlinearity, for nonlinearly absorbing and nonuniform plasmas, and for elliptically Gaussian laser beams. The Novikov‐Furutsu formalism has been followed to derive a parabolic equation for the average field, and the Akhmanov approach has been employed to solve this equation. It is concluded that the plasma turbulence tends to reduce the field intensity as the laser beam penetrates further. The self‐focusing‐induced oscillations of the beamwidth parameters and axial intensity become considerably aperiodic in the presence of turbulence; after a sufficient distance of propagation, an oscillating beamwidth parameter (axial intensity) starts increasing (decreasing) monotonically.

ISSN:0021-8979    

DOI:10.1063/1.327998

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We consider a theoretical calculation of a proposed atomic iodine laser system excited by a nuclear‐powered photon source. Overall system efficiency of 1.6% is calculated for the KrF fluorescent system and 2.3% for the Ar2F system. Laser power output of about 30 kW is estimated for a laser tube 1.8 cm in diameter and 60 cm long when used with a fast burst reactor. Such systems should easily scale to very high power.

ISSN:0021-8979    

DOI:10.1063/1.327999

出版商:AIP    

年代:1980

数据来源: AIP