摘要:

We report the direct measurement of each of the partial waves which constitute a surface acoustic wave propagating on ay‐zLiNbO3crystal by means of light scattering on internal reflection. It is shown both theoretically an experimentally that each of the partial waves has a wave vector pointing in a different direction. We could account theoretically for the shape of the scattered light which is split into several components. Each component corresponds to a single partial wave.

ISSN:0003-6951    

DOI:10.1063/1.90137

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

An interdigital transducer deposited on a piezoelectric substrate has been used to excite SAW on nonpiezoelectric materials by using a fluid couplant. The piezoelectric substrate is held at an angle to the nonpiezoelectric material so as to match the tangential k vectors of the surface waves. Experiments have been carried out with a LiNbO3piezoelectric substrate and a ceramic such as SiC or Si3N4with a fluid couplant. At a center frequency of 100 MHz, the estimated conversion efficiency of the surface wave from the piezoelectric to the nonpiezoelectric material is −3.5 dB. The results compare favorably with a normal mode coupling theory we have developed which predicts −2.7 dB efficiency.

ISSN:0003-6951    

DOI:10.1063/1.90138

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A monolithic metal‐ZnO‐SiO2‐Si SAW convolver has been developed which not only displays the advantages of the monolithic configuration, but also possesses, due to utilization of high coupling Sezawa waves, a wide bandwidth heretofore only exhibited by LiNbO3devices. We report here a bandwidth of 30 MHz at an input frequency of 225 MHz with a terminal efficiency of −56.9 dBm. The device displays an electromechanical coupling (&Dgr;v/v) of 0.019 which is the largest value yet reported for a ZnO device.

ISSN:0003-6951    

DOI:10.1063/1.90139

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A memory correlator using a matrix of Pt‐GaAs Schottky diodes airgap coupled to a LiNbO3substrate has been built. The high barrier potential of this type of junction (900 mV) leads to low diode leakage currents. As a consequence, storage time constants of up to 0.4 s have been measured at room temperature, while charging times can be as short as 10 ns. The other device characteristics are detailed, and particularly the possibility of correlating signals of several millisecond duration.

ISSN:0003-6951    

DOI:10.1063/1.90140

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The feasibility of using acousto‐optic frequency multiplexing to process several different signals simultaneously has been demonstrated. A four‐channel acousto‐optical system for correlating signals was operated successfully; each channel had a 45‐MHz bandwidth and a minimum of 45‐dB channel isolation.

ISSN:0003-6951    

DOI:10.1063/1.90115

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The unidirectionality of the ion current ina reflex tetrode has a result the efficient generation of pulsed ion beams. In this paper, experimental results are reported on the dependence of the ion‐generation efficiency, in a reflex tetrode, upon the applied voltage, total current, anode‐anode and anode‐cathode separations, applied magnetic field.

ISSN:0003-6951    

DOI:10.1063/1.90142

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Contributions from semiconductor plasma resonance and skin effect to the series resistance of Schottky barrier diodes are incorporated in a calculation of conversion loss for the submillimeter region. The calculation includes both intrinsic and parasitic losses and shows the conversion loss to be strongly dependent upon frequency of operation and upon diode diameter. At higher frequencies mixer performance may be optimized by careful choice of epitaxial carrier concentration and of diode size.

ISSN:0003-6951    

DOI:10.1063/1.90143

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We report the first demonstration of laser‐induced air breakdown at submillimeter wavelengths. An optically pumped D2O oscillator‐amplifier laser system which produced 75‐ns pulses at the megawatt level on the 385‐ and 359‐&mgr;m transitions was used. Focusing the 10‐cm‐diam laser beam with a 20‐ or 38‐cm‐focal‐length mirror onto an arbitrary surface to produce initial ionization caused multiple air breakdown plasmas with a threshold on the order of 1 MW cm−2. Theoretical (&ohgr;2+&ngr;2)/&ngr; scaling from the ruby and the neodymium laser air breakdown thresholds, where &ohgr; is the laser angular frequency and &ngr; is the electron‐molecule collision frequency, is in agreement with this initial experimental result.

ISSN:0003-6951    

DOI:10.1063/1.90116

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The resonance cone excited by a radio‐frequency antenna in a magnetoplasma is investigated in a large metallic plasma chamber. The large number of reflections of the resonance cone is found to be the explanation for the extensively observed and studied ’’Trivelpiece‐Gould’’ modes for a plasma‐filled waveguide. A dispersion relation is found, in close agreement with previous studies, which describes accurately the experimentally observed wavelike structures.

ISSN:0003-6951    

DOI:10.1063/1.90117

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Blistering of silicon due to argon bombardment has been observed at implantation energies above about 100 keV. Above about 200 keV rupture of blisters becomes the predominant surface damage phenomenon. Blistering effects are most obvious upon first appearance. Further bombardment causes the occurrence of new generations of blisters accompanied by oscillations in argon content of the silicon backing. The effects are interpreted in terms of argon agglomeration, build‐up of critical argon pressures, argon release from near‐surface regions, and sputtering.

ISSN:0003-6951    

DOI:10.1063/1.90118

出版商:AIP    

年代:1978

数据来源: AIP