摘要:

Typical rotary mechanical pumps, booster pumps, and diffusion pumps available today are described. Fundamental operating principles are discussed. The method for making theoretical computations of the conductance and speed of evacuation of a vacuum system is outlined.

ISSN:0034-6748    

DOI:10.1063/1.1741049

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A method for determination of very small concentrations of condensable vapors by measurement of the decrease in reflectivity of a cooled surface on which the vapor has been deposited is described. The method is applicable to mixtures of 2 components, one of which may be water. Use is made of the fact that a vapor will condense at a concentration below its vapor pressure in the presence of a second vapor whose liquid is soluble in that of the first. The most volatile component of the mixture is used in the pure state as a refrigerating agent whose evaporation cools the light‐reflecting surface to an accurately regulated temperature which produces condensation of the two components.An instrument embodying these principles is described which quantitatively measures triethylene glycol vapor in concentrations as low as 10−4mm Hg. The construction is simple and the operation continuous and automatic. The calibration of the instrument is presented. By proper adjustment, automatic compensation for changing atmospheric relative humidity can be secured so as to obtain response only to the degree of saturation of the glycol vapor in air.This device has been used to investigate condensation of vapors on atmospheric nuclei, and as a control instrument to regulate the concentration of triethylene glycol vapor employed as an aerial germicide for prevention of airborne disease transmission.

ISSN:0034-6748    

DOI:10.1063/1.1741048

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A description is given of an electronic sequence control circuit for the operation of a Wilson cloud chamber used in cosmic‐ray work. Necessary delays are introduced by unbalanced multivibrator circuits whose periods are adjustable by means of potentiometers. The circuit operating the magnetic‐type valve makes use of two thyratrons, one to conduct the valve current and the second, to interrupt it, permitting large values of this valve current and therefore fast action. Minor modifications readily adapt the circuit to a chamber used in other investigations.

ISSN:0034-6748    

DOI:10.1063/1.1741050

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The ion current from a Zinn‐type ion source has been determined for various values of three parameters of the source. These parameters are the diameters of the probe and plate holes and the spacing of the nose and plate. The ion current from the source was found to increase linearly with the diameter of the plate hole up to a certain value while above this value there was little further increase. The ion current likewise increased with probe hole diameter, but the increased gas flow prevented extensive increases in this parameter. A smaller gap between nose and plate gave the maximum ion current for a smaller current to the filament and therefore at a smaller power dissipation in the arc. Gas consumption was 10 cc per hour.

ISSN:0034-6748    

DOI:10.1063/1.1741051

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

An instrument capable of measuring the magnitude and polarity of electric fields at selected regions on an airplane in flight is described. The device covers a range of from 5 volts per cm to 4000 volts per cm in four steps with linear scales and is powered from a 28‐volt d.c. supply.

ISSN:0034-6748    

DOI:10.1063/1.1741052

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A circuit is described for providing unidirectional current pulses to a betatron magnet. By means of the resulting pulses of magnetic flux, electrons have been accelerated in a 22‐Mev betatron. Minor changes are necessary in the methods of electron injection and orbit expansion used with a continuously excited betatron magnet.

ISSN:0034-6748    

DOI:10.1063/1.1741053

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

If the normal functions of the grid and the plate of a conventional vacuum tube are interchanged, relatively large negative potentials applied to the plate can be measured as a function of the current drawn by one of the grids. By combining the characteristics of a tetrode operated in the inverted manner with a circuit employing a large amount of grid‐cathode degeneration, an instrument possessing an exceptionally high degree of stability has been constructed which is capable of measuring negative potentials from zero to 30 kilovolts. The indication is nearly linear with voltage and the input impedance is of the order of 1013ohms.

ISSN:0034-6748    

DOI:10.1063/1.1741054

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

This paper describes an electronic frequency meter capable of operating in the range from 20 c.p.s. to 200 kc. The reading of the instrument is independent of wave form as long as the input wave does not cross the zero axis more than twice in its fundamental period. For sinusoidal input, the voltage required for reliable operation is less than 0.03 volt r.m.s. between the frequencies of 900 c.p.s. and 200 kc. The sensitivity in the range below 900 c.p.s. can be readily increased by minor changes in amplifier coupling networks. Over a six‐month period, the experimental model has shown no change of calibration.

ISSN:0034-6748    

DOI:10.1063/1.1741055

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The conditions for measuring radioactivity in solution have been examined, and recommendations are given for optimum counting efficiency. The relative sensitivity of a dip counter has been found to compare favorably with other methods of counting, provided the beta‐radiation being measured has an energy of about 1 Mev or higher.

ISSN:0034-6748    

DOI:10.1063/1.1741056

出版商:AIP    

年代:1948

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1741058

出版商:AIP    

年代:1948

数据来源: AIP