摘要:

High‐frequency strain transducers consisting ofn‐channel piezoelectric DMOS transistors have been constructed. These transducers have detected surface acoustic waves at 20 and 28 MHz. The transducers exhibit gauge factors of the order of 105at dc.

ISSN:0003-6951    

DOI:10.1063/1.89169

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The radiation‐induced transformation from crystalline to amorphous silicon was studied using ion implantation. The ion energy was varied from 20 to 180 keV for Li+, N+, Ne+, Ar+, and Kr+. The energy dependence of the critical amorphizing dose was determined by electron spin resonance. Comparison of the data with theoretical calculations of the energy density deposited into atomic processes showed good agreement. This energy‐dependent agreement gave evidence that energy density is important to the transformation at both low and high implantation temperatures.

ISSN:0003-6951    

DOI:10.1063/1.89170

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A new type of airgap convolver has been constructed. It uses a mesap‐ndiode array, instead of the usual silicon slab, and narrow rails for supporting the diode array. Several different modes of operation for imaging have been demonstrated with this device.

ISSN:0003-6951    

DOI:10.1063/1.89171

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Ap‐njunction type storage convolver has been used to correlate FM chirps with time‐bandwidth products of approximately 90, and to correlate echoes from an acousticA‐scan system which have been badly distorted by the source transducer.

ISSN:0003-6951    

DOI:10.1063/1.89172

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Within the framework of classical beam theory it is shown that a strain‐independent surface stress has no effect on the natural frequency of a thin cantilever beam. Therefore, the experimental results of Lagowski, Gatos, and Sproles must have a different explanation.

ISSN:0003-6951    

DOI:10.1063/1.89173

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Using optical microscopy/etch pit techniques for the delineation of defects in {100} Czochralski silicon wafers we have made a one‐to‐one correlation between bulk stacking faults in oxidized wafers and etch hillocks identified at the same sites before oxidation. Transmission electron microscopy of the hillock defects shows them to be clusters of precipitates ranging in size from 0.01 to 0.3 &mgr;m. A discussion of these stacking‐fault nucleation sites in light of previous work on ’’swirl’’ defects in float‐zone wafers and attempts at preoxidation gettering are also presented along with a model for the formation of the extrinsic stacking faults.

ISSN:0003-6951    

DOI:10.1063/1.89174

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The possibility of preventing high‐voltage surface flashover of insulators in vacuum by means of a strong magnetic field perpendicular to the electric field and parallel to the insulator surface is investigated theoretically. A simple model predicts that with the right choice of insulating material one can design diodes and transmission lines so that the magnetic field from the line current inhibits the secondary‐electron‐emission avalanche which is believed to play an important role in the flashover process.

ISSN:0003-6951    

DOI:10.1063/1.89175

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Inversions in the population of excited levels in hydrogen and He II were observed in the FM‐1 spherator. The inversion increases strongly as the ratio of the decay time of the electron temperature to the decay time of the electron density was decreased. Time‐dependent numerical calculations of the populations were in good agreement with the experimental measurements. More general calculations for high‐Zhydrogenlike ions are discussed.

ISSN:0003-6951    

DOI:10.1063/1.89168

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The secondary electron energy distributions for a gold photocathode as excited by CK&agr;(277 eV) and AlK&agr;(1487 eV) x rays have been measured. The shapes of the energy distributions are essentially the same for these two x‐ray photon excitation energies. For thick evaporated gold samples on glass substrates (at 150 °C and 3×10−8Torr), the secondary electron energy distributions peak at about 1 eV and have a FWHM of about 4 eV. As measured immediately after ion cleaning, the distributions peak at about 2 eV and have a FWHM of about 6.6 eV. Approximately 5 h after ion cleaning, the measured distributions appear as those obtained before ion cleaning. The work function of the evaporated gold photocathode temporarily increases by 1 eV upon ion cleaning.

ISSN:0003-6951    

DOI:10.1063/1.89176

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We present a classical theory of stimulated Compton scattering by an intense relativistic electron beam. The growth rates in the x‐ray regime are obtained for two types of excitation: (i) an incident electromagnetic wave and (ii) a spatially rippled static magnetic field. Nonlinear spread of the beam velocity distribution by the pump field reduces the growth rate. The limiting growth rate depends only on the beam quality and becomes ∼1 &mgr;sec−1using the best available beam.

ISSN:0003-6951    

DOI:10.1063/1.89177

出版商:AIP    

年代:1976

数据来源: AIP