摘要:

Lithium ammonium sulphate LiNH4SO4has been shown to be the first of a new family of polar ferroelastic crystals which are not simultaneously ferroelectric. Stress‐induced shear twin motion in the ferroic phase below 10 °C verifies ferroelasticity, and the symmetry constraints are such that the prototypic polar axis does not change. From symmetry it is shown that only seven species of fully ferroelastic nonferroelectric polar ferroics are possible. Other crystals which may show this phenomenon are discussed.

ISSN:0003-6951    

DOI:10.1063/1.88396

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An optical image scanner which employs a piezoelectric delay line and transversal interrogation scheme is proposed. Linear scanning with a resolution of 16 lines/in. and a sensitivity of 35 &mgr;W/cm2have been achieved in a preliminary model. Estimates of limiting performance indicate the possibility of monolithic fabrication and resolutions in the region of 300 lines/in. using existing technology.

ISSN:0003-6951    

DOI:10.1063/1.88397

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The interaction of an intense relativistic electron beam with a mirror‐confined plasma was studied. Beam parameters were nominally 600 kV, 300 kA, and 15 kJ. A 12‐cm‐diam cold hydrogen target plasma withne∼2×1013/cm3was preformed in a 2:1 mirror system with a mirror spacing of 50 cm and peak mirror field of 0.8 T. Background fill pressures from 1 to 50 mTorr were used. Beam transport through the plasma was good and net current levels were low. Energy deposition levels were near 2×1017eV/cm3, consistent with expectations based on previous work. The use of tantalum anodes in order to increase the beam’s transverse velocity was found to quench the strong beam‐plasma interaction.

ISSN:0003-6951    

DOI:10.1063/1.88398

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A single‐pulse 30‐psec Nd‐YAG laser was used to induce five‐photon photoelectric emission from a gold metal cathode. The time and the spectral distributions were Gaussian. The pulse was selected from a mode‐locked pulse train and amplified. Theoretically predicted intensity dependence curves have been obtained with a certain decrease of the photoionization probability towards the high light intensities. The measured polarization dependence shows that the photoeffect is a surface one. However, an interesting effect was found, which seems to be connected with the phase relations of the oscillating em field components.

ISSN:0003-6951    

DOI:10.1063/1.88399

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A LaB6single crystal produced at the National Institute for Research in Inorganic Materials was used as an electron source of high brightness with a commercial‐type electron probe microanalyzer (EPMA). A single‐crystal tip of 0.2 mm &fgr;×4 mm was cut out from a mother crystal of LaB6obtained by discharge machining. The tip, held with Ta ribbons by electron beam welding, was mounted in a conventional tungsten hairpin filament holder which is commonly used in electron microscopes (CEM), scanning electron microscopes (SEM), and EPMA. Using this LaB6emitter in an electron gun of the commercial type EPMA, JAX‐3, instead of the conventional tungsten hairpin, the gun was operated under the same conditions as the tungsten hairpin: vacuum between low 10−4and high 10−5Torr, emission current ∼100 &mgr;A at 25 kV. It is concluded from a comparison of the scanning electron micrographs obtained with the LaB6emitter and the tungsten hairpin that the LaB6emitter can well be used instead of the conventional tungsten hairpins as an electron source of higher brightness for CEM and SEM even in such a low vacuum as ∼10−5Torr for practical use.

ISSN:0003-6951    

DOI:10.1063/1.88400

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Two‐dimensional distributions of the electron density within plasmas produced by 1‐nsec‐duration high‐intensity (≳1013W/cm2) CO2laser pulses on solid polyethylene targets have been obtained with the aid of microscopic holograhphic interferometry. Short 700‐psec pulses, derived from a synchronized ruby laser, were used to illuminate the interferometric system, which had a spatial resolution of ∼10 &mgr;.

ISSN:0003-6951    

DOI:10.1063/1.88401

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The power output of an iodine laser has been increased and the half‐width of the laser spike reduced by compressing the photolytically pumped laser gas with a shock wave. The deflection of the beam in the density gradient of the shock frontQspoils the laser cavity until the shock front has traversed the lasing volume.

ISSN:0003-6951    

DOI:10.1063/1.88402

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Surface properties of semiconductors may be determined by measuring the change in attenuation constant, acoustoelectric voltage, and convolution output of a semiconductor on a lithium niobate acoustic surface wave convolver structure. The change is caused by the application of a dc pulse voltage. Experimental results are presented for bothp‐ andn‐type silicon. The method is contactless, sensitive, and requires no sample preparation except polishing of one side. Also it is possible to study the variations of the semiconductor surface states along the direction of propagation of the surface wave by proper modification of this method.

ISSN:0003-6951    

DOI:10.1063/1.88403

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An automatic computer method for deriving the intensities, widths, and positions from experimental x‐ray diffraction and energy spectroscopy data is outlined. Complex overlapping clusters of peaks can be resolved and the data are corrected for aberrations.

ISSN:0003-6951    

DOI:10.1063/1.88404

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The geometric mismatch between semiconductor lasers and single‐mode optical fibers or diffused waveguides causes serious light loss. Transition fibers with cores that change shape from rectangular to circular can be used to reduce these losses. Techniques for fabrication of transition fibers with losses of 1 dB are discussed.

ISSN:0003-6951    

DOI:10.1063/1.88377

出版商:AIP    

年代:1975

数据来源: AIP