摘要:

This paper discusses the solution of the vector Laplace’s equation using the method of separation of variables to determine the magnetic field of three systems consisting of infinitesimally thin prolate spheroidal current bands and a ferromagnetic prolate spheroidal shell. Two configurations consist of a ferromagnetic spheroidal shell with an internal or external current band. The third configuration consists of a spheroidal shell with both internal and external current bands. The solutions are limited to dc currents and linear shell materials. They provide a method for calculating the interaction between the ferromagnetic material and the current band for symmetric and nonsymmetric current bands and a prolate spheroidal shell.

ISSN:0021-8979    

DOI:10.1063/1.331287

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The exposure characteristics of six polymer resists to 1.5 MeV H+, He+, and O+ions and to 20 keV electrons were measured. The resists used were polystyrene (PS), polymethyl methacrylate (PMMA), PMMA mixed with 20% of a copolymer of vinyl acetate and vinyl chloride (VMCC), poly(glycidyl methacrylate‐co‐3‐chlorostyrene) (GMC), poly(butene‐1‐sulfone) (PBS), and a novolac. The deposited energy per unit volume required to expose a resist was found to be a function of the spatial energy dissipation rate of the ion in the resist. This has been accounted for in terms of the nature of the energy distribution around the primary particle track in conjunction with whether the resist requires the activation of a single site or two adjacent sites to produce exposure.

ISSN:0021-8979    

DOI:10.1063/1.331261

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

An amplifier on cold, relativistic, guided electron beams is considered. The problem is reduced to a set of first‐order, linear, ordinary differential equations. The dispersion relation governing the stability of the system is derived and its solutions are studied numerically. The results of the calculations show that in the submillimeter regime, the spatial growth rates in the system may be comparable to those predicted for Raman‐free electron lasers.

ISSN:0021-8979    

DOI:10.1063/1.331262

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The dependence of pulsed CO2laser performance, in terms of efficiency and power output, on circuit configuration has been investigated. It has been shown that the type of circuit used to excite the laser can significantly affect its performance. The variation of laser output with circuit has been shown to be consistent with a change in the value ofE/Nat which energy is transferred into the glow discharge.

ISSN:0021-8979    

DOI:10.1063/1.331263

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We present a detailed analysis of the plasma conditions required to optimize gain in two proposed x‐ray lasing schemes using resonant photo‐pumping. In one proposed configuration, the Si XIII line 1s2‐1s2p1Pat 6.650 A˚ pumps Al XII 1s2−1s3p1Pat 6.635 A˚, inverting the Al XIIn= 3 andn= 2 levels which are separated by 44 A˚. A similar approach which utilizes the Na X 1s2‐1s2p1Pline at 11.00 A˚ would invert then= 4, 3, and 2 levels of Ne IX. Conditions in the pumped neon and aluminum plasmas, and in the pumping silicon plasma, are calculated using a multistage, multilevel atomic model with multifrequency radiation transport. For modeling the pumping sodium line we have inferred the intensity from a spectrum of a neon filled, laser‐imploded glass microballoon containing sodium impurities obtained at Rochester. The pump line intensities calculated for Si and inferred for Na are equivalent to blackbodies of 252 and 227 eV, respectively. It is found that peak gain for the 3‐2 lines of about 100 cm−1occurs at ion densities of 1020cm−3and 4×1020cm−3in the pumped neon and aluminum plasmas, respectively. Temperatures required to maximize gain in the pumped plasmas are found to be 50 and 100 eV, for neon and aluminum, respectively. Finally, since the silicon and aluminum lines are slightly off resonance, we have investigated the effect of streaming the plasmas toward each other at various velocities to offset some or all of the wavelength difference. It is found that a streaming velocity of 6.8×107cm sec−1—fully offsetting the wavelength difference—will approximately triple the achieved gain compared to the zero velocity case. Lesser increases in gain occur with partial velocity offsets.

ISSN:0021-8979    

DOI:10.1063/1.331264

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Facet degradation of InGaAsP/InP double‐heterostructure (DH) lasers in accelerating environment of water was studied from the standpoint of quantitative comparison with GaAlAs DH lasers. Facet degradation of InGaAsP/InP DH lasers proceeds by oxidation mechanism and its degradation rate is 2–3 orders below that of GaAlAs DH lasers. The difference of oxidation behavior between InGaAsP/InP and GaAlAs DH lasers was examined by using large wafers having the same composition as lasers. The following results were obtained: the oxidation proceeds with the inward diffusion of molecule water through the oxide film, the oxidation rate ofn‐InP is more than two orders of magnitude lower than that ofn‐GaAs, In oxide and P oxide were uniformly distributed in the depth profile of the oxide for InP and InGaAsP, and As oxide has the abnormally depleted distribution in the front layer of the oxide for GaAs and GaAlAs. The facet degradation rate is influenced by some experimental factors, i.e., the optical output power, the injection current in dc‐biased experiment, and the water temperature in unbiased experiment. To explain the degradation behavior caused in dc‐biased and unbiased experiment under identical mechanism, we attempted to evaluate the degradation rate as a function of the facet temperature; the optical output power and the injection current in dc‐biased experiment were assumed to contribute to the supplying source of carriers, which rapidly recombine nonradiatively, raise the facet temperature, and finally promote the diffusion of molecule water through oxides and the reaction rate at oxide‐facet interface. Combining these results with the fact that the oxidation rate varies in proportion to the partial pressure of a molecule water in the operation environment, we estimated the degradation rate of InGaAsP/InP DH lasers operated under 6.7 mW/&mgr;m2at 70 °C in a nearly dry nitrogen environment (relative humidity of 1–10%).

ISSN:0021-8979    

DOI:10.1063/1.331265

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

This paper describes a model for the physical behavior of a painted surface when irradiated by a high‐energy laser. The model proposes that the paint degrades to a residue which adheres to the surface and whose optical and thermal properties control the coupling of the radiation to that surface Experimental observations are presented which confirm the theoretical predictions of the model. Measurements of the intensity‐dependent absorptance of the surface of painted A12024 alloy plates agree with calculated values when appropriate values of the thermophysical properties of the paint residue are chosen.

ISSN:0021-8979    

DOI:10.1063/1.331266

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The use of a plasma medium for the compression of KrF laser light to pulse widths suitable for laser‐driven fusion applications is described. The results indicate that efficient pulse compression can be realized. A particular feature is the absence of the troublesome backward second‐Stokes wave found in gas cell compressors.

ISSN:0021-8979    

DOI:10.1063/1.331267

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The temperature dependence of the refractive index of SrTiO3, near room temperature, has been found to be −5.1×10−5 °C−1at 632.8 nm by a variation of the minimum deviation prism method. We found that this temperature dependence had to be included to account correctly for the observed temperature sensitivity of coupling light to lithium niobate optical waveguides with strontium titanate prisms.

ISSN:0021-8979    

DOI:10.1063/1.331268

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

From deconvolution of the echo scattered by a surface, it is theoretically possible to obtain the impulse response of this scatterer. In some cases, this response can be closely related to the geometry of the scatterer and can be used for its characterization. In practice, even in the field of ultrasonic spectroscopy, the transducers always exhibit a finite bandwidth. We suggest a method for extending the Fourier spectrum which leads to better results after deconvolution. The experiments are performed with targets consisting either of small plane surfaces with various shapes, or of large randomly rough surfaces. The results are in good agreement with those expected using the Kirchhoff‐Helmholtz approximation.

ISSN:0021-8979    

DOI:10.1063/1.331269

出版商:AIP    

年代:1982

数据来源: AIP