摘要:

The electron backscattering coefficient and reflected energy for surface films on bulk substrates have been computed using the photon‐electron Monte Carlo transport codesandyl. The calculations were done for the film/substrate configurations Al/Pt, Ag/Pt, Ag/Al, and Au/Al with incident electron beam energies of 20, 40, 60, and 100 keV at different angles of incidence and various film thicknesses. The backscattering results are compared with available experimental data taken at normal incidence.

ISSN:0021-8979    

DOI:10.1063/1.335629

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Longitudinal space‐charge forces can be neglected in computer simulations of slowly curving quasilaminar electron beams. A particle‐mesh‐type algorithm for transverse space‐charge forces is developed, and great simplification in numerical calculation of asymmetric electron beams is demonstrated. Some typical examples for kinescope beams are discussed.

ISSN:0021-8979    

DOI:10.1063/1.335630

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Reconstruction of current density in electron beams is complicated by distortion of phase space which can require very fine discretization of the beam into trajectories. An efficient discretization of phase space is exploited, using conservation of charge and current in hypertriangle patches, to reconstruct the current density by fitting Gaussians through the distorted hypertriangles. Advantages and limitations are discussed.

ISSN:0021-8979    

DOI:10.1063/1.335631

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Enhancement of the microwave magneto‐Kerr effect in semiconductors is discussed for the semiconductor being preceded by a semi‐infinite dielectric and by a quarter‐wave dielectric slab for both plane‐wave and guided‐wave cases. Expressions are developed that relate the amount of the enhancement to the relative permittivity of the dielectric. Experimental results are compared to the theoretically obtained expressions for the quarter‐wave case and the experimentally obtained values compare favorably with the theory.

ISSN:0021-8979    

DOI:10.1063/1.335632

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new type of dichroic reflector has been developed for the far‐infrared region of the spectrum, based onn‐type germanium with a diffused conduction layer. A 111‐axis single‐crystal plate of 40‐&OHgr; cm optical‐grade germanium was implanted with 5×1014As+ions/cm2by ion bombardment at 200 keV; the donor impurity ions were subsequently diffused into the substrate at a temperature of 850 °C (held for 20 h). The measured power‐reflection spectrum displayed a shallow minimum at ∼70 cm−1, rising steeply below 50 cm−1to reach 80% reflectivity at 10 cm−1. Computer modeling of the infrared reflectance of a thermally diffused conducting layer inn‐type germanium—with the assumption of Conwell–Weisskopf mobility variation for the conduction electrons—gave an excellent fit to the observed reflection spectrum for an integrated column density of 1014cm−2and 10‐&mgr;m half width, the latter being in good agreement with the value &sqrt;Dt=11 &mgr;m calculated for thermal diffusion under the conditions indicated.

ISSN:0021-8979    

DOI:10.1063/1.335633

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A model is proposed which links electron beam propagation through plasma into a vacuum with collective ion acceleration from the plasma. Electron reflection from the virtual cathode at the beam front transfers momentum to the ions, and a moving ion channel is formed allowing the electron beam to propagate. A momentum‐balance equation is derived, and theoretical results for the ion velocity are in good agreement with the experimental data. Conditions for transverse beam confinement are discussed.

ISSN:0021-8979    

DOI:10.1063/1.335634

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Monte Carlo simulation techniques are used to study the electron transport properties in the high electric field region near the pin in negative pin‐plane corona discharges in atmospheric air. The results of the calculations show that the discharge electrons are nearly in equilibrium with the high local electric field near the pin tip. Consequently, a simpler computational model can be used to predict the voltage‐current characteristics of these discharges. The results also show that ionization growth is very rapid for the pin‐tip radii, gap lengths, and applied voltages which have been studied experimentally.

ISSN:0021-8979    

DOI:10.1063/1.335635

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An intense vacuum ultraviolet spike 0.2 &mgr;s in width is observed at the initial stage of low‐pressure Xe discharge, i.e., Xe Townsend discharge, in submillimeter tubes. The intensity of the 147 nm resonance line reaches 1.3 W/cm2, about 200 times stronger than that obtained from the steady‐state Xe positive column. Efficiency of the vacuum ultraviolet radiation exceeds 24%, or 32 lm/ W when green phosphor is excited, four times higher than that of the positive column, or more than an order of magnitude higher than that of the negative glow. This high intensity and efficiency originate from the optimized electron energy which can be adjusted externally by changing the electric field and pressure, contrary to that in the positive column or negative glow. Another important feature of the Townsend discharge is its wide dynamic range of operation, which is advantageous when driving a panel having a large number of cells with scattered discharge characteristics. Consequently, a gas discharge display panel utilizing the Townsend discharge has more than an order of magnitude higher efficiency than the positive column or negative glow panels.

ISSN:0021-8979    

DOI:10.1063/1.336278

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The lattice parameter of a cubic nickel‐based alloy, MAR‐M200, has been determined as a function of pressure for 0<p<14 GPa at room temperature. A similar study was made for Ni3Al in the range 0<p<11 GPa at room temperature. In both cases, the diamond anvil pressure cell was used in conjunction with the energy dispersive method of x‐ray diffraction. The data were analyzed in the context of model equations of state and in comparison with other results from ultrasonic studies.

ISSN:0021-8979    

DOI:10.1063/1.335636

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Depth profiles of 300‐keV protons implanted inn‐type GaAs at room temperature have been obtained using secondary ion mass spectrometry and correlated with optical effects determined by infrared reflectance measurements. The profiles of the implanted hydrogen (1H) have been measured as a function of annealing for temperatures up to 600 °C. These profiles display a major redistribution of the hydrogen atoms with movement beginning at 200 °C and terminating by 700 °C. The hydrogen diffusion into the substrate can be approximated by an Arrhenius process with an activation energy of 0.62 eV and a diffusion constant of 1.54×10−5cm2/s. The reflectance spectra indicate that while an optically uniform layer is present in the as‐implanted specimen, more complicated optical profiles exist in the annealed samples. Annealing at 300 °C causes the layer to nearly double in thickness but higher temperature annealing produces optical profiles similar to the as‐implanted state. Qualitatively, these optical changes follow the behavior of the hydrogen depth profiles.

ISSN:0021-8979    

DOI:10.1063/1.335637

出版商:AIP    

年代:1985

数据来源: AIP