摘要:

The small signal gain spectra of a 10.4‐&mgr;m band of a TEA CO2laser have been measured and a distinguishable gain anomaly of aR(14) line of the 10.4‐&mgr;m band has been revealed. This gain anomaly due to sequence band overlapping has been found to be responsible for the appearance of aR(14) line in the multiline oscillation of a TEA CO2laser. The characteristics of multiline oscillation using a temperature controlled ZnSe etalon have been analyzed in detail by use of the measured small signal gain spectra and temperature‐ and wavelength‐dependent etalon reflectivities.

ISSN:0021-8979    

DOI:10.1063/1.327907

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple two‐layer model explaining all the main features of angular and voltage dependences of light transmission through twisted nematic liquid‐crystal devices is proposed. The model is based on the physical symmetries of the twisted nematic structure and, for the first time, provides a qualitative description of transmission patterns without need for detailed calculations.

ISSN:0021-8979    

DOI:10.1063/1.327908

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Acoustic emission activity during hydride formation in tantalum atCH=7.2 at.% was detected as a function of temperature by measuring the ringdown count rate, the total number of events, and their amplitude distributions. Elastic modulus and internal friction measurements were also conducted in the same specimen to provide evidence of H precipitation. There are indications that, as in niobium, the acoustic emission phenomenon is caused by cracking at the precipitate particles.

ISSN:0021-8979    

DOI:10.1063/1.327909

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The coefficient of electrical resistance of manganin was measured under shock loading and ramp unloading. We made 64 measurements of loading stress in the 1.3–40.5‐GPa range and 22 measurements of unloading stress in the 1.9–23.2‐GPa range. The average loading coefficient was 14% larger than the average unloading coefficient—a clear measure of resistance hysteresis. The source of the hysteresis is attributed to an irreversible resistance change in manganin caused by shock damage. We present techniques to correct for the effects of this irreversible resistance change. With this correction, both loading and unloading levels showed the same average coefficient of resistance 0.0221±0.004 per GPa. Our unified calibration procedure can be very useful for analyzing complex stress signals that are produced, for example, by reactive shock waves.

ISSN:0021-8979    

DOI:10.1063/1.327910

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In a cylindrical high‐pressures lamp, filled with Ar, Hg, NaI, and TlI, the plasma composition is determined by the fully vaporized Hg and the vapor pressures of NaI and TlI. The vapor pressures are controlled by the temperature and composition of the liquid iodide mixture at the coldest spot of the lamp. The calculations of the concentration profiles of all species have been performed using measured temperature profiles. The calculations take into account concentration diffusion and ambipolar diffusion. Using these concentration profiles the local absorption coefficients for the Na‐D and the Tl‐535 nm lines are evaluated regarding the broadening by Hg atoms. After solving the radiation transport equation the line shapes are calculated. A comparison of the calculated line shapes with the measured ones shows good agreement.

ISSN:0021-8979    

DOI:10.1063/1.327911

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simplified technique for electron density measurements in laser‐type uv photoplasmas is described. This modified microwave transmission approach requires a minimum of test equipment and provides all data necessary for a full time analysis of the photoplasma from only a single photographically recorded pulsed measurement. Accuracy is comparable with that of conventional interferometers but speed and simplicity are much improved.

ISSN:0021-8979    

DOI:10.1063/1.327912

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A mass accelerator system using a series of imploded annular plasma pinches to propel projectiles of mass ranging from grams to kilograms up to high velocities is analyzed theoretically. Such a device would have applications ranging from basic materials and impact studies to space‐probe launching and impact fusion.

ISSN:0021-8979    

DOI:10.1063/1.327913

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Two PLT‐injector‐type duoPIGatron sources, modified further by shaping the beam‐forming apertures, have been tested and experimented on a protype beam line similar to the ISX‐B neutral beam injection system. The accelerator column modification has resulted in an increase of the beam power transmission efficiency from that of the straight‐bore aperture by 50%. Maximum neutral beam powers achieved on a 28‐cm‐diam target simulating the ISX‐B plasma, located 4.1 m downstream from the source, are ?910 kW of H0at an accelerator power of 42 kV and 61 A and ?1020 kW of D0at 43 kV and 55 A. Measurements have been made to investigate the following: the effects on beam optics of aperture shape, aspect ratio, and different ions (H+or D+); the distribution of beam power deposition along the beam line; ion species compositions; and background pressure behavior due to scrape‐off beam particles. The injectors have been shown to be characterized by an optimum perveance of 6×10−6AV−3/2for an effective extraction area of 142 cm2(1799 apertures), which is approximately invariant over the beam energies tried (viz., 25‐45 keV).

ISSN:0021-8979    

DOI:10.1063/1.327914

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Penetration profiles of P+ions with energy between 70 and 150 keV incident 7.5° off the ⟨100⟩ axis on silicon covered with a SiO2layer of thicknesses ranging from 0.05 to 0.20 &mgr;m were studied both experimentally and by computer simulation. Electrical measurements were routinely performed, but occasionally CAMECA ion‐probe measurements were carried out to obtain chemical profiles. For a given energy of implantation, maximum penetration occurs when the oxide thickness produces an angular spreading of the misaligned incident beam with maximum transmitted intensity along the crystallographic direction. This suggests that the tails are due to a channeling process, in agreement with the finding by Bloodetal. in bare silicon. It is also shown that diffusion occurs after 1/2‐hannealing at 900 °C, implying the presence of a high‐diffusivity region around the penetration tail.

ISSN:0021-8979    

DOI:10.1063/1.327915

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Depth‐resolved cathodoluminescence was employed in conjunction with layer removal by chemical etching in an investigation of the anomalous postrange damage introduction which accompanies shallow ion implantations in ZnTe. 200‐keV Xe+implantations were performed at substrate temperatures of 300 or 80 K; the latter implant was postannealed at 300 K. The calculated projected range of these implants was 0.05 &mgr;m. However, 10‐ to 1000‐fold quenching of the incumbent extrinsic and intrinsic ZnTe luminescence was found at depths of 1–2 &mgr;m following both implants. In comparison to the 300 K implant, the 80 K implant and subsequent 300 K anneal introduces postrange defects at a higher concentration and the highly damaged region extends to a greater depth. Injection level dependence measurements show that the predominant effect of the postrange defects is to introduce independent nonradiative recombination centers rather than to react with the incumbent luminescence centers. However, we presently have no clue to the identity of the defect species introduced. In conclusion, we discuss the implications of the anomalous defect introduction for the device technology of ZnTe.

ISSN:0021-8979    

DOI:10.1063/1.327916

出版商:AIP    

年代:1980

数据来源: AIP