摘要:

X‐ray conversion efficiencies in 351‐nm laser‐produced plasmas are investigated. X‐ray line emissions, which are useful for x‐ray shadowgraphy, have been characterized by studying dependencies on laser pulse duration, irradiation intensity, target material, and target structure. The conversion efficiencies decrease with increasing x‐ray energy and markedly decrease with increasing laser intensity. A microparticle on a plastic plate is tested in an attempt to develop a point x‐ray source. This target shows a higher conversion rate than a microwire target due to reduction in energy dissipation through hydrodynamic expansion.

ISSN:0021-8979    

DOI:10.1063/1.345486

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The Rutherford backscattering technique has been used to determine the depth profile of Xe+and Xe2+implanted into amorphized quartz crystal at energies from 50 to 400 keV. Based on Biersack’s angular diffusion model, an efficient method has been developed for comparison with experimental data. The results show that the measured mean projected range is in quite good agreement with calculated value for first‐order treatment. A marked improvement in range straggling is obtained after considering the second order energy loss. Also the results are compared to transport of ions in matter prediction.

ISSN:0021-8979    

DOI:10.1063/1.345487

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A novel Cs+ion source combining the advantages of porous metal ionizers with those of zeolite emitters has been developed. Cesium ions are chemically stored in a cesium‐mordenite solid electrolyte (Cs‐M SE) pellet whose emitting surface is coated with a porous tungsten thin film. Cesium supply to the emitting surface is controlled by a voltage applied across the solid electrolyte pellet. Cs+ion emission takes place on the surface of the porous tungsten electrode by surface ionization. The ionic conductivity of Cs+ion in the Cs‐M SE is of order of 10−5&OHgr; cm−1at 1000 °C. The interface properties between electrolyte and electrodes play a major role in the cesium ion source. The cathode electrode interface (emitting electrode) determines the stability of the supply current density to the emitting surface. The lifetime of the source is found to depend on the anode interface. In a steady‐state operation, an ion‐emission current density of the order of 20 mA/cm2has been extracted for 30 h at a total ion‐emission current of 100 &mgr;A at 1000 °C. This corresponds to 10 C of extracted charge.

ISSN:0021-8979    

DOI:10.1063/1.345458

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Three‐dimensional analysis of a heat‐spreading phenomenon in a heat sink of phase‐locked arrays of oxide‐isolated diode lasers is carried out in the present paper. The main result is that with increasing number of laser elements the heat‐sink temperature increase turns out to change sublinearly whereas temperature differences between adjacent edge lasers increase considerably which threatens stability of the phase‐locking operation. The heat spreading in semiconductor, contact, and solder layers was approximated by a one‐dimensional model. The special correction factor (b) accounting for the two dimensionality of this heat spreading was used to improve the accuracy of the calculations.

ISSN:0021-8979    

DOI:10.1063/1.345459

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Preionization electron densities have been studied in an x‐ray preionized XeCl laser as a function of the gas composition. Also the influence of emission of photoelectrons from the electrode surfaces on the initial electron density has been determined. For low Xe partial pressures, an excited neon bottleneck in the Penning ionization process of Xe is found. For higher Xe pressures, the preionization density increases linearly with the Xe concentration. A simple model gives a satisfactory agreement with the measurements over more than two decades of Xe partial pressure. We also determine the density of Ne* following x‐ray irradiation. Measurements in mixtures containing HCl show that due to electron attachment no initial value of the electron density can be assigned. The method used here will give a lower estimate for the total charge density in these mixtures.

ISSN:0021-8979    

DOI:10.1063/1.345460

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

On the basis of a plane‐wave analysis we develop an original one‐dimensional model for the nonlinear Fabry–Pe´rot e´talon. This model facilitates numerical analysis and physical interpretations. We discuss the role of diffraction and the influence of the incident angle on bistability. A preliminary numerical study of the model is proposed.

ISSN:0021-8979    

DOI:10.1063/1.345436

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Three‐dimensional computer calculations which analyze time‐transient behavior of heat conduction and phase‐change kinetics in an InSbTe overwritable disk were made. To improve the calculation accuracy, thermal conductivities of thin‐film materials and critical cooling rate for crystallizing the recording film were estimated. For realization of high‐performance overwrite, it was found that the cooling conditions of writing and erasing processes should be controlled to match the critical cooling rate in a given linear velocity range. This could be achieved by optimal design of the disk structure.

ISSN:0021-8979    

DOI:10.1063/1.345437

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present a formalism to treat Faraday rotation (FR) in composite media. The method isnotlimited to low concentrations of magnetically active inhomogeneities and is thus useful for understanding the magneto‐optical properties of such inhomogeneous media over the whole range of concentrations. It involves the calculation of an effective magnetic‐field‐dependent dielectric tensor@s&egr;eusing a tensor effective‐medium approximation. To illustrate the technique, we present the results of several model calculations involving both paramagnetic and ferromagnetic metals. We find that such materials have strongly enhanced FR over a wide range of frequencies. The effects of particle shapes on FR are discussed.

ISSN:0021-8979    

DOI:10.1063/1.345438

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In this paper, electromagnetic wave propagation and mode coupling in a chirowaveguide are treated using the coupled‐mode theory. A chirowaveguide, as defined in our previous work, is a conventional cylindrical waveguide filled with homogeneous chiral materials. A set of coupled linear differential equations is derived for various mode amplitudes in the waveguide. We then show that, in any single chirowaveguide, owing to the handed properties of chiral materials filling the waveguide, energy coupling occurs from one mode to the other. We also demonstrate that in a parallel‐plate chirowaveguide a TE mode can be completely converted into a TM mode and vice versa as they propagate in the guide. Thus a chirowaveguide can indeed be used as a mode converter. Selected results are compared with those reported in the literature. Applications of such mode coupling in the design of novel microwave, millimeter‐wave, and optical devices and components are mentioned.

ISSN:0021-8979    

DOI:10.1063/1.345439

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A general theoretical approach to the modeling of several different process steps in fabrication of ion‐exchanged channel waveguides is presented. All of the commonly used fabrication processes are included, and the nature of the ion source and the effect of external electric voltage are taken into account. The model uses a numerical finite‐difference calculation of diffusion in the glass with boundary conditions and electrical current distribution chosen according to the process being modeled. A single computer program includes the model, and can be used for simulating a fabrication process with different successive process steps. Several calculated examples are given, all with experimentally obtained parameters for Ag+‐Na+exchange in Corning 0211 glass.

ISSN:0021-8979    

DOI:10.1063/1.345440

出版商:AIP    

年代:1990

数据来源: AIP