摘要:

The application of ionization gap or ``pin'' probes to measure flame velocities during the development of detonation is presented. Probe construction and circuit techniques are described which, despite the widely varying character of the ionization signals in this region, yield timing precision of 2% or less for hydrogen‐oxygen mixtures. Analysis of the ionization probe circuit permits the identification of the probe signal with the ionization levels encountered in the various waves generated during the development of detonation. In this manner it is possible to differentiate between shocks, flames, and detonation waves and to determine the axial flame velocity profile.

ISSN:0034-6748    

DOI:10.1063/1.1716819

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The selective diffusion of hydrogen in palladium has been employed to determine the presence of hydrogen qualitatively and quantitatively in different gas mixtures. It was found possible to determine concentrations of hydrogen from 100% to 0.001%, or about ten parts per million, in nitrogen, with ease. Also it was found possible to detect the presence of hydrogen at a partial pressure of 10−7mm Hg. This would indicate that it is possible to determine the presence of hydrogen in concentrations of one part in 1010in a gas at atmospheric pressure. There is reason to believe that this technique could be extended even further perhaps to one part in 1014with proper care and presently existing high vacuum techniques.

ISSN:0034-6748    

DOI:10.1063/1.1716820

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Experiments in which silicon p‐n junctions have been used as detectors of fission fragments and elastically scattered heavy ions are described. The curve of pulse height versus energy for carbon particles is linear and passes through the origin. Points for Cf252fission fragments and alpha particles fall on the curve determined by the carbon‐particle points. This result implies that the energy required for electron‐hole pair formation is the same for the three types of particles. Also, no ``ionization defect'' is observed for the fission fragments. Some other possible uses for the detectors of this type are suggested.

ISSN:0034-6748    

DOI:10.1063/1.1716821

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A two‐core flux‐gate magnetometer is employed in a simple balanced bridge circuit as the dc field detector of a single strip permeameter. The sensitive magnetometer and simple bridge circuit eliminated the necessity of the complex filter and selective amplifier used in earlier systems and allows operation independent of oscillator frequency stability. The H‐measuring system is designed to measure fields from 1 moe to about 10 oe with a sensitivity of ≈25 &mgr;a/moe. Economy and simplicity of construction, circuitry, and operation are its chief advantages.

ISSN:0034-6748    

DOI:10.1063/1.1716822

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Experimental work is described in which pressure fluctuations as great as two orders of magnitude as recorded by a new type of cold‐cathode vacuum gauge were undetected by a Bayard‐Alpert ionization gauge. It is shown that the Bayard‐Alpert gauge measures the pressure inside its electron‐accelerating grid only and not that within the remainder of the evacuated system. Operation of the heated filament of this gauge within a glass tube or near glass parts gives rise to sodium, potassium, and other low ionization‐potential materials throughout the vacuum system but in spite of being a major source of contamination, the Bayard‐Alpert gauge does not detect the presence of these substances. This is because such low ionization‐potential materials are photoionized by the light from the heated filament and cannot penetrate the positively charged electron‐accelerating grid in order to be detected. Some other effects related to the phenomenon are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716823

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A small high performance double focusing mass spectrometer employing a 90° electrostatic analyzer and a 60° magnetic analyzer is described. The radius of curvature of ion paths in the magnetic analyzer is 2 in. As a laboratory instrument for making gas or isotope analyses, its sensitivity and resolution make it competitive with instruments several times as large employing only a magnetic analyzer. With a permanent magnet the weight and power consumption are both low, making it attractive for applications where these factors may be of importance.

ISSN:0034-6748    

DOI:10.1063/1.1716824

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A simple system is described for maintaining controlled experimental temperatures between the normal boiling points of helium and nitrogen. No special apparatus is involved other than that normally required for the handling of liquid helium and the measurement of low temperatures. The technique has been used to control the temperature of a resonant cavity to within ±0.2°K, forT>20°K, using a copper‐Constantan thermocouple and a variable range recording potentiometer to measure temperature.

ISSN:0034-6748    

DOI:10.1063/1.1716825

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Factors affecting the performance of filamentary scintillators are considered. Experimental data on light attenuation for both plastic scintillator filaments and thin‐wall glass tubing liquid scintillators are presented. A theoretical interpretation which satisfactorily accounts for the performance of luminescent filaments in terms of bulk properties and surface reflection losses is given and permits quantitative evaluation of surface losses for various materials. While plastic scintillator fibers are mechanically convenient, it is suggested that liquid‐filled fibers will prove more consistent and stable in their properties. Comments on the utility of arrays of fibers as particle track imaging devices and as image intensifier screens are included.

ISSN:0034-6748    

DOI:10.1063/1.1716826

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A mechanically simple magnetic balance having sufficient sensitivity to measure diamagnetic susceptibilities has been developed using a permanent magnet. Its operation is based on the twisting of a quartz or Vycor fiber in a direction such as to overcome the effects of the magnetic field. The magnetic field strength is dependent on the position of the magnet with respect to the sample and can be varied by using different magnet settings.

ISSN:0034-6748    

DOI:10.1063/1.1716827

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A new method for spin‐echo self‐diffusion measurements is presented. The magnetic field gradient, instead of the rf pulse interval, is varied; hence, the oscilloscope sweep and pulser settings need not be changed during measurements. Requirements onH1are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716828

出版商:AIP    

年代:1960

数据来源: AIP