摘要:

A high resolution system for the measurement of the energy loss spectra of 20–250 keV heavy ions incident on gas targets is described. The high resolution is obtained by decelerating the ion beam to a low, well defined energy before performing the energy analysis. The energy loss spectrum is determined by changing the accelerator energy to compensate for energy lost in collisions with the gas atoms. The system is arranged so that normal fluctuations in the accelerator's power supply do not affect the energy resolution. The resolving power of the system is 2.5×104. The primary proton beam has a detected WHM of 2 V at 50 kV. An energy loss spectrum is shown for which the collision‐excited 11S‐21Ptransition in helium is clearly resolved.

ISSN:0034-6748    

DOI:10.1063/1.1684061

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We report the development of a new ellipsometry technique which is especially well suited to the measurement of the dielectric constants of high reflectivity metals. Modulation methods are used to permit the measurement of a differential reflectance parameter which does not decrease in sensitivity in the high reflectivity limit as do the usual reflectance parameters measured with standard techniques. In addition the ellipsometer is faster than previous methods, being capable of recording the relevant data in a few minutes as the wavelength is swept continuously over a range of several thousand angstroms. The precision of the dielectric constants so measured is 1% in most cases. The polarization modulation technique, upon which the ellipsometer is based, is presented in detail, with emphasis on its wider applicability to any problem involving the study of dichroic phenomena.

ISSN:0034-6748    

DOI:10.1063/1.1684062

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The apparatus described by Jasperson and Schnatterly [Rev. Sci. Instrum.40, 761 (1969)] was modified to allow direct measurement of the derivatives of the optical dielectric functions of solids with respect to wavelength. The modifications are described and measurements of ∂&egr;1/∂&lgr; and ∂&egr;2/∂&lgr; are presented for metallic silver in the wavelength range 3300–4000 Å.

ISSN:0034-6748    

DOI:10.1063/1.1684063

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A system for analyzing waveforms consisting of mixtures of exponentially damped sine waves is described. The instrument generates a set of damped sine waves of variable amplitude, frequency, damping decrement, and phase. These waveforms are added and displayed on an oscilloscope. Their parameters can be adjusted to obtain a waveform which matches the curve to be analyzed. The component waveforms are then analyzed one at a time. The instrument has been used to analyze interferometer curves arising in the course of plasma wave experiments.

ISSN:0034-6748    

DOI:10.1063/1.1684064

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A broad band correlation technique using anx‐yoscilloscope has been developed. When two noise signals are applied to the inputs of the oscilloscope, a characteristic pattern is formed on the oscilloscope face. It is shown that an equal intensity contour of the pattern, which may be obtained by photographing, is an ellipse and that the correlation depends only on the eccentricity and the angle of inclination of the ellipse. The bandwidth of this correlator is only limited by the oscilloscope. The instrument has been used to measure the correlation between fluctuations measured by two spatially separated probes in a plasma.

ISSN:0034-6748    

DOI:10.1063/1.1684065

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We have measured the low temperature specific heat (1.6 to 4 K) of six commercial aluminum alloys (ASM types 7075, 7079, 2219, 2014, 2618, and 2024). The results are given in the form of fits to the relationC=&ggr;T+BT3. Some alloys show deviations from this relation at the lowest temperatures. This may be due to the presence of 3dtransition elements in these alloys.

ISSN:0034-6748    

DOI:10.1063/1.1684066

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A thin jet of liquid issuing from a nozzle at a high velocity disintegrates spontaneously into droplets under the action of surface tension. A periodic disturbance of the jet can be used to control the disintegration so as to make all droplets of the same size. A system for generating monodisperse sprays according to the principle outlined above has been designed and built. The jet is modulated by axial vibration of the nozzle, which is mounted at the center of a membrane. The membrane is vibrated by means of electrostrictive elements. Droplets in the diameter range 40–15 &mgr; have been produced at a vibration frequency of 20–300 kHz. The stream of droplets has been analyzed in several ways. A jet of air perpendicular to the droplet stream has proved to be of special value. Several air jets, pulsed in suitable phase relations, are utilized to disperse the stream of droplets and to prevent the droplets from coalescing during the drying phase of the aerosol generation.

ISSN:0034-6748    

DOI:10.1063/1.1684067

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Measurements of the well known electron impact spectra of helium show that a retarding field energy analyzer can give spurious responses; these can be minimized but not eliminated by careful adjustments of the operating potentials. Probable sources of the trouble are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1684068

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A pulse radiolysis apparatus with photometric monitoring has been built around an 11 MeV, 250 mA peak current, linac that delivers single 0.25 to 4 &mgr;sec pulses. The novel features of the apparatus include (1) a 450 W xenon lamp as the analyzing light source which in pulsed operation had a 25 times increased luminance; (2) a fast electronic switch that cut out the signal due to the Cˇerenkov radiation; (3) a secondary emission chamber that allowed the simultaneous measurement of the current and the direction of the pulsed electron beam; and (4) a system for remote controlled change of liquid samples stored in glass syringes. Reliable measurements of optical transmission could be made starting 0.2 &mgr;sec after the electron pulse at wavelengths down to 2000 Å on transient species having products of yield and absorptivityG×&egr;>500 mole (100 eV)−1·liter−1·cm−1.

ISSN:0034-6748    

DOI:10.1063/1.1684069

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A model for rapid mixing of liquids is developed to relate driving pressure and time needed for complete mixing. A quantitative statement of this relationship is obtained by replacing turbulence with diffusion and employing Stokes' law for the viscous forces. Mixing times predicted by the model compare reasonably well with several values reported for different jet‐type mixer designs.

ISSN:0034-6748    

DOI:10.1063/1.1684070

出版商:AIP    

年代:1969

数据来源: AIP