摘要:

Numerical models to calculate temperature distributions during laser chemical vapor deposition (LCVD) of spots and during the direct writing of lines are presented. The temperature variation of the thermal conductivities of the substrate and the deposit are taken into account in both models. Results are used to study the LCVD deposition of platinum spots and lines on pyrex glass substrates.

ISSN:0021-8979    

DOI:10.1063/1.347293

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Insitunitrogen‐ion implantation of polycrystalline niobium and tantalum was performed and the surface was characterized by x‐ray photoelectron spectroscopy (XPS). The XPS chemical shifts indicated the formation of metal nitride. The chemical shift values are calculated theoretically and compared with the experimental values.

ISSN:0021-8979    

DOI:10.1063/1.347294

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A method for ultraclean radioactive marking is presented, utilizing the process of nuclear stimulated desorption. It employs a sequence of two slow radioactive decays. The primary decay causes a nucleus to desorb from a substrate onto which it had been placed. The desorbing daughter nuclei, being themselves radioactive, then constitute an ultraclean marking flux. A manifestation of this mechanism for the special case of the47Ca→47Sc→47Ti decay is described. An application to end‐point detection in wet etching is presented and quantitatively simulated.

ISSN:0021-8979    

DOI:10.1063/1.347295

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An electron beam can be trapped in a stellatron accelerator with a passive technique by dissipating the energy associated with the poloidal displacement of the beam from its equilibrium position. If the net force on the beam is directed toward the minor center of the vacuum chamber, the beam will spiral toward its equilibrium position. The beam dissipates energy by charging and discharging a conductor that is grounded through a resistor. Numerical solutions in the paraxial approximation illustrate this capture effect, with parameters that show a large enough effect to trap a beam.

ISSN:0021-8979    

DOI:10.1063/1.347296

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The operation of a cesium beam tube optically pumped with cesiumD1andD2lines is theoretically and experimentally investigated. In a single laser diode configuration using theD2line, the most efficient excitation scheme is found to be the 3→3&sgr;(D2) scheme leading to a clock signal‐to‐noise ratio equal to 15 000 in a one‐hertz bandwidth. In the case of theD1line, the predicted best excitation schemes are the 4→3&pgr;(D1) and the 4→3&sgr;(D1) schemes. However, these two configurations lead to an extra fluorescence noise presumably due to unpumped atoms. The 3→4&pgr;(D1) scheme is experimentally found to be the best with S/N performances comparable to the 3→3&sgr;(D2) configuration. Nevertheless, in the case of the 3→3&sgr;(D2) scheme, optical pumping efficiency decreases when the magnetic field is too low whereas 3→4&pgr;(D1) features are independent of the magnetic‐field amplitude. Moreover, the well‐separated fluorescence lines in the case of theD1line allow a more accurate locking of the laser frequency on the top of the fluorescence line than in the case of theD2line. A perfectly symmetrical microwave spectrum results when the 3→4&pgr;(D1) scheme is used.

ISSN:0021-8979    

DOI:10.1063/1.347297

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The calculation of the quasistationary current distribution and the magnetic field strength in conductors of discontinuous cross section needs some numerical effort. In this article, a method is derived to calculate the resultant current distribution by integrating incremental field strength distributions due to infinitesimal currents fed to one of the conductors in the common part of the conductors cross section. The method is applied for a coaxial line of axial discontinuity to demonstrate the accuracy of the approximate solution compared to the exact field distribution which can be also given for the selected example.

ISSN:0021-8979    

DOI:10.1063/1.347298

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Kukhtarev equations are solved taking into account the photovoltaic effect and different boundary conditions. In the case of open circuit, the voltage across the crystal is found to vary with a time scale similar to the photorefractive time constant. This effect explains the dynamic behavior observed experimentally.

ISSN:0021-8979    

DOI:10.1063/1.347299

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The electro‐optical constants of 2‐Methyl‐4‐Nitroaniline crystals are measured at a wavelength of 632.8 nm. The results confirm the measurements made by Lipscomb, Garito, and R. S. Narang [J. Chem. Phys.75, 1509 (1981)] for the first time and settle the descrepency between Tokura, Kurita, and Koda experiment [Phys. Rev. B31, 2588 (1985)] and Lipscomb, Garito, and R. S. Narang.

ISSN:0021-8979    

DOI:10.1063/1.347300

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The far‐field pattern of a large‐scale amplifier array (LSAA) consisting of a large number (2000) of diode laser amplifiers is numerically simulated, and the power collection efficiencies are determined. Random distributions of phase mismatches, misorientations, and element failures in the LSAA system are considered. Phase mismatches and misorientations of the element amplifiers are found to be the most critical parameters of those affecting the power‐collection efficiency. Errors of 0.2&lgr; and 25% for phase and diffraction angle, respectively, cause a 10% reduction in power‐collection efficiency. The results are used to evaluate the concept of space‐laser power transmission. It was found that an overall transmission efficiency of 80% could be realized with a 5‐m‐diam. receiver at a distance of 10 000 km when an LSAA transmitter 6 m in diam. is aimed with state‐of‐the‐art pointing accuracy.

ISSN:0021-8979    

DOI:10.1063/1.347301

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of a gas cooling system on the efficiency of an average‐power solid‐state disk laser amplifier is addressed. Such a configuration has application in solid‐state fusion drivers. Analytical models are discussed that identify the important parameters in specifying an optimized laser and optimized cooling system. It is shown that the penalty that the cooling and conditioning system power requirements have on the overall laser system efficiency can be easily maintained below 10%, particularly for large‐aperture systems.

ISSN:0021-8979    

DOI:10.1063/1.347302

出版商:AIP    

年代:1991

数据来源: AIP