摘要:

We consider the deformation, due to surface stress, of an elastic crystal in the shape of a square. We reduce the problem to one of linear elasticity and obtain a solution using the finite‐element method.

ISSN:0003-6951    

DOI:10.1063/1.89371

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Repetitive pulses from lasers with pulse widths 5–10 nsec or a current generator with 10–25‐nsec widths have been used to launch acoustic waves by thermoelastic expansions. For the laser case, when transparent media such as quartz plates are used to acoustically constrain the energy absorbing surface, an increase of up to 46 dB at 20 MHz was observed over that generated from a free surface. An experiment using a scannable laser to generate elastic waves for flaw detection in a metallic sample is described.

ISSN:0003-6951    

DOI:10.1063/1.89375

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A direct determination is made of the total power radiated in a single pulse,F P(&ohgr;)  d&ohgr;, by an intense relativistic electron beam cyclotron maser configuration as a function of applied magnetic field. The existence of other possible instabilities over a broad spectral range notwithstanding, the total output is dominated by the maser instability occurring at the relativistic cyclotron resonance magnetic field. The results for two different anode‐cathode spacings, corresponding qualitatively to cold and warm beam conditions, are presented and compared. A possible explanation accounting for the existence of high power noise radiation at low magnetic fields for the warm beam case is discussed.

ISSN:0003-6951    

DOI:10.1063/1.89376

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Measurements have been made of the attenuation of radiation of &lgr;=10.6 &mgr;m by a plasma initiated by an electrical spark in air. The light transmission varied from <2% to ≳10% as the input laser energy ranged from 300 mJ to < 0.1 mJ. These results indicate that the spark‐initiated plasma acted as a seed plasma for the laser. The trend of increasing attenuation with increasing incident laser energy is promising for use as an isolator in high‐power laser systems.

ISSN:0003-6951    

DOI:10.1063/1.89377

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Point‐contact Schottky diodes have been used to detect 10.6‐&mgr; radiation. Best results were obtained withn‐Ge/W contacts. These gave voltage responsivity about an order of magnitude larger than typical metal‐oxide‐metal point contacts under zero‐bias conditions, although with higher source impedance.

ISSN:0003-6951    

DOI:10.1063/1.89378

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The characteristics of the radiation from channeled relativistic electrons and positrons are discussed and model calculations carried out. Radiation near 2.5 keV associated with transitions etween the 2 p→1seigenstates of 2‐MeV electrons channeled along the ⟨110⟩ axis of MgO is predicted with 50 times the usual bremsstrahlung intensity in a 10% bandwidth. Recent low‐energy bremsstrahlung measurements made with 28‐MeV electrons propagating along an axis in silicon are interpreted in terms of this model.

ISSN:0003-6951    

DOI:10.1063/1.89379

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

It is demonstrated that by covering a tungsten surface with tungsten needles, the sputtering coefficient for He ions is reduced by a factor of 3 to 100. Also, this metal surface does not blister under He bombardment to doses of 2.8×1019He/cm2, although a similar polished W surface blisters at 1/30 this dose. Sputtering yields have been determined for both monoenergetic and distributed energy He ion beams, and the angular distribution of sputtered ions is reported.

ISSN:0003-6951    

DOI:10.1063/1.89380

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Phase holograms have been formed in pure outdiffused LiNbO3waveguides using the photorefractive effect initiated by two‐photon absorption. Efficient holograms were recorded with two guided waves, of less than 100 W peak power, and less than 10 &mgr;J optical energy. This technique automatically compensates for wave front perturbations in the guide and allows the formation of various integrated components such as wavelength multiplexers and optical switches.

ISSN:0003-6951    

DOI:10.1063/1.89363

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Experiments have been conducted to determine the feasibility of the theoretical experiment set forth by Cazaux. The experiment consists of electron bombarding a thin foil of aluminum with a thin specimen mounted on the opposite side. A focused scanning electron beam is used to bombard the aluminum substrate to produce a localized source of AlK&agr; x rays. This focused Al x‐ray (h&ngr;=1.4 keV) source creates a spatially localized source of photoelectrons in the specimen. The photoelectrons are separated in energy with a cylindrical mirror spectrometer to produce an ESCA spectrum from an area of less than 20 &mgr;m in diameter. Two‐dimensional ESCA images have been obtained by this method utilizing intensity variations in the amplitude of a selected photoelectron peak to intensity modulate a cathode ray tube monitor as the electron beam is scanned.

ISSN:0003-6951    

DOI:10.1063/1.89364

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The first observation of dc‐electric‐field‐induced$optical rectification is eported. In this process a dc polarization is produced in a medium (in this case nitrobenzene) by the simultaneous presence of dc and optical electric fields. The relation between this process and the Kerr effect is found to be consistent with that predicted by permutation symmetry. A bolometerlike response also seen in these experiments is discussed.

ISSN:0003-6951    

DOI:10.1063/1.89365

出版商:AIP    

年代:1977

数据来源: AIP