摘要:

Electron diffraction studies of 4Hb‐TaS2have shown that layers with octahedral (OC) and trigonal prismatic (TP) coordination undergo independent transitions to charge density wave states similar to those in 1T‐TaS2(pure OC) and 2H‐TaS2(pure TP), respectively. This is in agreement with the transitions observed in physical properties such as the electrical resistivity, magnetic susceptibility, and heat capacity for this material.

ISSN:0003-6951    

DOI:10.1063/1.89043

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A permanent echo following a two‐pulse write sequence which has been observed from piezoelectric powders is also observed in other types of powders. It is shown that a simple model in which the echo originates from the mechanical alignment of particles is consistent with all known echo properties.

ISSN:0003-6951    

DOI:10.1063/1.89044

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A fresnoite (Ba2Si2TiO8) single crystal was grown from the melt by the Czochralski method. Synthetic fresnoite has an electromechanical coupling factor in the thickness shear mode ofk15=0.28, and a resonance‐frequency temperature coefficient in this mode ofTfr=−33 ppm/°C. Fresnoite is considered to be superior to Ba2Ge2TiO8for various piezoelectric applications because of the absence of microtwins observed in Ba2Ge2TiO8.

ISSN:0003-6951    

DOI:10.1063/1.89045

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Temperature‐dependent structure in the photoenhancement of nonlinear surface‐acoustic‐wave convolution on ZnO is reported. Measurements of the temperature dependence of surface‐wave convolution without light, thermally stimulated conductivity, and photoconductivity suggest that the photoenhancement effect in ZnO is sensitive to trapping and surface preparation. A possible model for the dependence of photoenhancement on photon wavelength is proposed.

ISSN:0003-6951    

DOI:10.1063/1.89046

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The behavior of DT‐filled implosion targets with very low‐Z(carbon) ablators irradiated by 1‐MeV electrons is compared to that with intermediate‐ and high‐Zablators. The inner part of the pusher is of lower entropy due to decreased bremsstrahlung heating. The DT is shielded from compression until later in the energy pulse, when it is more strongly compressed. However, thicker ablators transfer less energy to the pusher; hence, diamond‐carbon ablators perform better than graphite‐carbon. Precompression of graphite‐carbon with a laser does not reduce the minimum power required for break‐even, but does lead to increased gain above break‐even.

ISSN:0003-6951    

DOI:10.1063/1.89047

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The self‐trapping of laser beams in underdense plasmas or the propagation of laser beams in preformed favorable electron density distributions can be accompanied by gross distortions of pulse shape and spectrum. A simple theory is used to estimate the magnitude of these effects.

ISSN:0003-6951    

DOI:10.1063/1.89048

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The peak electron density in e‐beam‐excited rare‐gas plasmas has been studied as a function of pressure, using inverse bremsstrahlung absorption techniques. It was found that the heavier rare gases exhibit broad maxima beyond which the peak electron density decreases monotonically with pressure. No maxima were observed in helium or neon over the pressure range investigated (0–400 psia). Data are presented along with a proposed theoretical explanation for the observed phenomena.

ISSN:0003-6951    

DOI:10.1063/1.89049

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We have obtained multiple‐shock compression of a gas by the application of a tailored power pulse. Density increases well beyond the compression of a single strong shock were reached. No second shock could be launched if the second power step exceeded the first one by a factor of 10.

ISSN:0003-6951    

DOI:10.1063/1.89050

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The first operation of a cw CO chemical laser delivering nearly 1 W of power oscillation on the 1→0 vibrational band is reported. Experimental results and operating details with respect to 1→0 emission are discussed. Optical pumping of CO by the CO chemical laser is also reported; optically pumped absorption has been measured up to the 6→5 band.

ISSN:0003-6951    

DOI:10.1063/1.89030

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We present an analysis of optically pumping Rydberg states in alkalis to generate coherent lasers in the infrared and far‐infrared spectral regions. Based on the previous accurate experimental and theoretical data on these states, our conclusion is that such laser systems can be operated either pulsed or cw and possess narrow linewidths, high gains, and considerable tunability. Wavelengths near 16, 12, 8.6, and 7.7 &mgr;m which are of interest for isotope separation are achievable with milliwatt power levels. Specific examples for Na vapor are given.

ISSN:0003-6951    

DOI:10.1063/1.89031

出版商:AIP    

年代:1976

数据来源: AIP