摘要:

This paper describes the two‐dimensional field generated by anMpole electromagnet of cylindrical symmetry. By individually controlling the currents on each pole, it is possible to rotate the direction of the field around the axis of the cylinder. Gradients of any order can also be generated. The dependence of the power on the physical dimensions of the whole magnet and on the gap region is also discussed.

ISSN:0021-8979    

DOI:10.1063/1.336638

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The ability of spectroscopic ellipsometry to analyze the multilayer surface structure of an implanted semiconductor with 1–2 A˚ resolution has been demonstrated. Spectroscopic ellipsometric data from 1.5 to 4.5 eV on a number of self‐ion‐implanted silicon samples have been analyzed using the regression analysis technique. It is shown that such a procedure can yield information nondestructively and in a nonperturbing manner: (i) on the depth profile of multilayer structures; (ii) quantitative information on the thicknesses of each layer (within 90% confidence limits); (iii) the structure (whether crystalline or amorphous) as well as the degree of crystallinity in the region; (iv) characterize the oxide layer if present on specimen; and (v) microroughness of the surface, if present. Furthermore, it is shown that these results are in excellent quantitative agreement with the completely independent results obtained on the same specimens using cross‐section transmission electron microscopy.

ISSN:0021-8979    

DOI:10.1063/1.336639

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We present a new method of easily displaying optical‐beam‐induced contrast (OBIC) images from scanning optical microscopes. The new technique which displays the rectified, differentiated OBIC signal, is insensitive to variations in the background signal level.

ISSN:0021-8979    

DOI:10.1063/1.336585

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Instability mechanisms discussed to date are unable to account for the behavior of long‐pulse self‐sustained discharge‐pumped XeCl devices. We develop theoretical arguments supporting the concept that halogen donor depletion during the discharge pulse is the principal cause of discharge collapse and the termination of lasing. The theoretical prediction that the duration of the glow phase should vary as the inverse square of the initial halogen donor concentration is verified by experimental results furnished by a study of a resistively stabilized long‐pulse xenon chloride laser.

ISSN:0021-8979    

DOI:10.1063/1.336586

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This paper describes an x‐ray preionized avalanche discharge‐pumped XeCl laser capable of producing output pulses of greater than 250‐ns FWHM duration and energies of ∼1 J. This represents the longest pulse duration yet reported from such a high‐power laser. Nevertheless, the laser output pulse is shown to terminate while the laser is still apparently under strong electrical excitation. The severity of this premature laser termination has been found to be dependent on both the partial pressure of the halogen donor molecule, HCl, in the laser gas mixture, and on the magnitude of the electrical excitation rate. Investigations of the discharge homogeneity, using time‐integrated and time‐resolved photographic observation of the discharge, scattering of a short duration dye laser probe beam, and time‐integrated and time‐resolved fluorescence spectra of species within the laser gas mixture have led to the conclusion that it is the formation of small, discrete current channels in the body of the discharge which is the prime cause of the premature termination. These scatter the laser radiation and also lead to nonuniform and inefficient formation of the excimers.

ISSN:0021-8979    

DOI:10.1063/1.336587

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Tellurium suboxide (TeOx) films prepared by coevaporation consist of tiny grains of tellurium embedded in a TeO2matrix. The size of the tellurium grains depends on the preparation conditions. Except for samples with exceedingly small grains, crystalline diffraction patterns can be observed by using selected‐area electron diffraction even though these samples show amorphous x‐ray diffraction patterns. Heat treatment causes a transition in optical properties and the appearance of peaks for crystalline tellurium in x‐ray diffraction. Thermal writing with a focused diode laser on both heat‐treated and as‐deposited samples gave recorded marks with high sensitivity and good contrast, although an incubation period of many seconds is required for the full development of the marks. The observed laser recording behavior cannot be explained by a simple amorphous‐to‐crystalline transition, and a new writing mechanism is proposed.

ISSN:0021-8979    

DOI:10.1063/1.336588

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The average kinetic energy of the atoms sputtered from the copper cathode of a magnetron sputtering discharge has been deduced from the shapes of their Doppler‐broadened emission lines, which were measured with a high‐resolution scanning Fabry–Perot interferometer. At a fixed distance from the cathode the energy decreased with increasing sputtering gas pressure, as expected. The experimental points fell between the theoretical curves of Westwood [J. Vac. Sci. Technol.15, 1 (1978)], and Meyer, Schuller, and Falco [J. Appl. Phys.52, 5803 (1981)] lying somewhat closer to the former than to the latter.

ISSN:0021-8979    

DOI:10.1063/1.336589

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Beam extraction simulations for high‐voltage, immersed source accelerators are compared with analytic theory and experiment.dynadisc, a new nonlinear beam propagation code, is described and applied to the initial few meters of propagation in 1 atm air. Thedynadiscresults indicate that filamentation is the fastest growing instability. The filamentation changes the beam current density profile from an annular to a quasi‐uniform distribution.

ISSN:0021-8979    

DOI:10.1063/1.336590

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The influence of superelastic electronic collisions from the metastable CO(A3&Pgr;) state on the electron energy distribution functions (EDF’s) of CO in both discharge and post‐discharge conditions has been studied by solving the Boltzmann equation with different concentrations (cm) of CO(A3&Pgr;). The results show that the role of CO(A3&Pgr;) becomes more important as the reduced electric field (E/N) is lowered. Very small concentrations of CO(A3&Pgr;) (cm &bartil; 10−7) are sufficient to affect EDF in the post‐discharge regime (E/N=0). Superelastic electronic collisions are such that they create different plateaus in EDF, each one spaced approximately every 6.2 eV, which represents the energy threshold of the metastable electronic state.

ISSN:0021-8979    

DOI:10.1063/1.336591

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Near the critical layer, laser radiation linearly mode converts into a Langmuir wave which attains a large amplitude and influences the Weibel/quasimode via a four‐wave parametric process involving two Langmuir wave side bands. The growth rate for this process is obtained. Under certain conditions it is shown that a linearly unstable Weibel mode is suppressed by the pump wave.

ISSN:0021-8979    

DOI:10.1063/1.336592

出版商:AIP    

年代:1986

数据来源: AIP