摘要:

A parametric study was made of the pulsed hollow discharge duoplasmatron, operating as a negative hydrogen ion source in the pure hydrogen mode and in the mixed hydrogen–cesium mode. Effects of the arc current, gas pressure, and the magnetic field on the extracted H−current were investigated for different electrode geometries and potentials. In the hydrogen mode a maximum H−beam current of 11 mA was obtained from an anode extraction aperture of 2.45‐mm diameter, with a normalized emittance of 0.1&pgr; cm mrad. In the mixed hydrogen–cesium mode an H−beam current of 60 mA was obtained from the same aperture. At a current of 40 mA the normalized emittance was 0.23&pgr; cm mrad. An analysis of the results points to the volume production of H−ions in the hydrogen mode and to the surface production in the hydrogen–cesium mode.

ISSN:0034-6748    

DOI:10.1063/1.1134570

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A highly sensitive tunnel diode trigger useful in temporal intensity buildup measurements of mode‐locked lasers has been developed; the device reduces notably the time walk due to the lack of repeatability in intensity of the laser output. The performance of the trigger has been established by means of a 5‐GHz wideband, 0.1 V/cm sensitive real‐time oscilloscope and of an image converter camera of picosecond resolution. The experimental results show that a variation of the amplitude of the laser pulse train of a factor of 5 leads to a time jitter of less than 30 psec.

ISSN:0034-6748    

DOI:10.1063/1.1134571

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A device to detect small vibrations, which we call a flux gradient accelerometer, has been constructed. We propose to use such a device as the transducer for a low‐temperature gravitational wave detector. The accelerometer is found to respond as predicted by a simple harmonic oscillator model with a sensitivity nearly equal to the sensitivity calculated theoretically. If the accelerometer signal were amplified by a SQUID (superconducting quantum interference device) having a flux noise of 1.4×10−12G cm2 Hz−1/2, the signal should just equal the noise when &Dgr;xrms=9×10−18(&Dgr;f)−1/2cm where &Dgr;xrmsis the rms displacement, and &Dgr;fis the amplifier bandwidth.

ISSN:0034-6748    

DOI:10.1063/1.1134572

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An optical system for measuring the slope of random wind‐generated water waves is described. The instrument employs the refraction of a vertical light ray, which is a technique that has been previously used. The present system, however, employs a large‐area array of individual photovoltaic cells to measure the refraction angle of the beam. Because the array provides a much larger active area with no preferred direction, it is much better suited to the measurement of random water wave fields, typical of those generated by wind.

ISSN:0034-6748    

DOI:10.1063/1.1134573

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A 10‐keV atomic beam source of hydrogen atoms in then=44 or other selected state was based upon charge exchange production of then=10 state followed by Doppler‐tuned cw CO2laser excitation to the desired highly excited state. In present operation the output atom flux of the source is 2.5×105sec−1, a value that can be increased by as much as 105. The technique can be extended to considerably higher and lower atom energies, to a wide range of atom quantum numbers, and to atoms other than hydrogen.

ISSN:0034-6748    

DOI:10.1063/1.1134578

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Holographic interferometry and finite element analysis have been applied to determine the strain in a large optical window installed in a high‐pressure chamber. Two different shapes of windows were chosen, and the outside and inside surface strains of the windows were followed as a function of internal pressure by taking double exposed holograms at 69‐bar intervals up to 483 bars. The results were compared with the values calculated by a standard finite element code with an assumption of no displacement at the load‐bearing edge. The agreement between two results was found to be good for both cases.

ISSN:0034-6748    

DOI:10.1063/1.1134552

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A heterodyning modulation technique is described which results in an improved sensitivity for the superconducting chopper amplifier. Dc sensitivities of 3×10−12V were obtained in a 1 Hz noise bandwidth. An experimental comparison of various modulation schemes is presented.

ISSN:0034-6748    

DOI:10.1063/1.1134553

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A sensitive instrument is described that measures the frictional and normal forces while nearly parallel fibers are rubbed in various media at normal forces down to 1 mg and rubbing speeds slow enough to ensure continuous contact. Typical frictional output traces are shown for human hair and coarse mohair fibers in water. The instrument detects scale engagement of keratin fibers.

ISSN:0034-6748    

DOI:10.1063/1.1134554

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A freestanding transmission grating has been used as a dispersive element in a simple monochromator. The monochromator, to be used with the collimated light beam from a resonance lamp radiation source, has been tested in the far uv with the helium and neon emission spectra. The results show that the simple monochromator will resolve all major lines in the emission spectra. A high efficiency into first‐order diffracted beams is obtained, and the efficiency is independent of photon energy. The results show that the resonance lamp–transmission grating combination is a unique source of monochromatic light for photoemission and optical work in the far uv region. More advanced monochromator designs and the possibility of extension of the monochromator for use at x‐ray energies are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1134555

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A device is described for holding and stretching thin unsupported sheets or fibers near the plane of a slide surface on the microscope stage. Photographs of the instrumental details are shown. Specimens can be not only stretched, observed, and photographed on the microscope stage, but the clamped material can, while in the device, be removed from the microscope, treated by heating (cooking), freezing, or fixing; and returned to the microscope for further observation or prepared for sectioning. Shop drawings are available.

ISSN:0034-6748    

DOI:10.1063/1.1134556

出版商:AIP    

年代:1976

数据来源: AIP