摘要:

An infrared tunable acousto‐optic filter based on Tl3AsSe3in a noncollinear configuration is described. The filter was operated at CO2laser wavelengths from 10.8 to 9.3 &mgr;m, with corresponding rf drive frequencies in the 15–18‐MHz range. Filter bandwidths are of the order of 20–30 cm−1, and the measured tuning rate is 18.0 kHz/cm−1at 10 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.90583

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have used for the first time the electron‐microscopy technique to reveal the pure ferroelastic phase domain structure of lead phosphate, Pb3(PO4)2. The domain configuration confirms previous identifications of the symmetry elements lost at the transition. The domains are found separated by thin walls whose thicknesses are less than 50 A˚. This and other recent studies suggest narrower walls in ferroelectrics and in ferroelectric ferroelastics than were envisaged from earlier theoretical models. The very high values reported by different authors are believed to be due to the resolution limitations of the experimental setup used. Fruitful consequences are expected from a thorough understanding of the stresses and lattice distortions associated with the ferroelastic domain structure.

ISSN:0003-6951    

DOI:10.1063/1.90594

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have obtained two consecutive ion pulses separated in time by 2.6 msec from a long‐pulse (1–2 &mgr;sec) reflex tetrode ion source. The source voltage is 100 kV and the ion current density is 0.7 A/cm2. Calorimetry indicates that the energy in two pulses is equal to 180% of that in the first pulse for delays of ≳2.6 msec. For shorter delays the energy in the second pulse is reduced due to premature shorting of the diode.

ISSN:0003-6951    

DOI:10.1063/1.90566

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A planar receiving antenna with a predictable pattern at submillimeter wavelength is demonstrated experimentally for the first time. It is single lobed and efficient, with a gain of approximately 8 dB at a wavelength of 119 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.90574

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Ionization of liquid gallium coated on a tungsten field‐ion tip was investigated using a magnetic‐sector atom probe. For the first time, both the energy distribution of ionized Ga and its critical energy deficit with respect to a tip potential were measured as a function of field and tip temperature. Without heating the gallium, a stable Ga+ion current of up to 10 &mgr;A was obtained from a small surface area of a tip with an energy distribution of less than 12 eV FWHM.

ISSN:0003-6951    

DOI:10.1063/1.90578

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The design, fabrication, and testing of conical laser fusion targets is described. These are DT‐filled conical holes in lead, 190 &mgr;m deep and covered with a 132‐&mgr;m‐diam plastic cap. The results of two‐dimensional simulations of the cones are displayed. Experimentally, up to 2.8×105neutrons have been obtained from the exploding pusher implosion of such a target under single‐beam CO2illumination of the cap at 0.13 TW.

ISSN:0003-6951    

DOI:10.1063/1.90580

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The lifetime of stressed silica fibers is normally limited by moisture‐enhanced stress corrosion cracking known as static fatigue. We have developed a metal‐jacketing technique that provides a hermetic protection of the glass fiber surface. Fibers protected in this fashion appear to be immune to normal static fatigue effects. Lifetimes of stressed silica fibers with hermetic jackets have been observed to be more than five orders of magnitude longer than those of conventional plastic‐coated fibers.

ISSN:0003-6951    

DOI:10.1063/1.90581

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A comparison of ac and dc thermocurrents in &ggr;‐phase‐containing PVF2films prepared by different techniques isolates spectral features unique to &ggr;‐phase crystallites. The spectral changes that result from theinsituthermal conversion of &ggr;‐ and &agr;‐phase‐containing films provides a self‐consistent verification of assignments.

ISSN:0003-6951    

DOI:10.1063/1.90582

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The instantaneous (9 &mgr;sec) two‐dimensional concentration in a turbulent jet has been measured by imaging the Mie‐scattered light from a seeded flow onto a low‐light‐level TV camera and processing the data in a computer. The average concentration and rms concentration fluctation profile, as well as the spatial concentration fluctuation correlations, have been obtained.

ISSN:0003-6951    

DOI:10.1063/1.90584

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Cermet solar selective surfaces of absorptance over 0.90 and emittance less than 0.05 have been prepared by vacuum coevaporation of alumina and spinel with gold, silver, chromium, and copper. Grading of commposition was employed to enhance the absorptance. The effect of heat treatment in vacuum up to 500 °C was studied and the chromium‐alumina cermet shown to be the best candidate for vacuum‐insulated collectors.

ISSN:0003-6951    

DOI:10.1063/1.90585

出版商:AIP    

年代:1979

数据来源: AIP