摘要:

The Kelvin vibrating condenser method of measuring electrostatic potential has been applied to the measurement of screen potential in cathode‐ray tubes. Results indicate that it will work satisfactorily in such an application, and it promises to be a useful tool in obtaining information on the charging phenomena of phosphors and insulators.

ISSN:0034-6748    

DOI:10.1063/1.1715276

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A hot wire thermal diffusion column of the type described by Clusius and Dickel has been constructed to increase the concentration of tritium in tritium‐hydrogen mixtures. The column, 350 cm long and 2.86 cm in diameter, produced an equilibrium separation factor of 680 when filled to a pressure of 64 cm of mercury with hydrogen containing 3.5 percent tritium.

ISSN:0034-6748    

DOI:10.1063/1.1715277

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A circulating pump designed to give a constant rate of flow of gases, even at sub‐atmospheric pressures, is described. The pumping mechanism consists of a reciprocating piston in a cylinder driven at a constant linear speed. The valves in a double‐acting valve system have been made ``weightless'' by the use of solenoids. Mercury is used as a displacement fluid.

ISSN:0034-6748    

DOI:10.1063/1.1715278

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An all‐metal ultra‐high vacuum valve is described. The valve has a continuously variable conductance from about 1 l/sec to less than 10−14l/sec and presumably as small as desired. An equilibrium method of measuring small leakage conductances is described.

ISSN:0034-6748    

DOI:10.1063/1.1715279

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The mutual capacitance between hemispherical electrodes which are separated by a distance less than one‐tenth of their radii is found experimentally to vary directly with the logarithm of the spacing. A mathematical derivation is presented which suggests that such a relation should hold. A particular electrode‐dielectric assembly may be calibrated at large spacings where accurate mechanical measurements can be made, and then the capacitance increment corresponding to any desired smaller spacing may be obtained by a simple linear extrapolation. Electrode separations as small as 1 &mgr; have been determined to an accuracy of less than 5 percent with this technique.

ISSN:0034-6748    

DOI:10.1063/1.1715280

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An apparatus for measuring resistivity and Hall coefficient of semiconductors is described. Using a new type of measuring circuit, it combines the best features of both ac and dc apparatus. Thus, on the one hand, errors due to thermal emf's and the Ettingshausen effect are eliminated while, on the other hand, the one necessary balance is still made on a simple dc potentiometer with a dc galvanometer as null indicator. Contact and lead resistances do not affect the readings. Results of resistance and Hall coefficient measurements on a germanium specimen are given as an indication of performance.

ISSN:0034-6748    

DOI:10.1063/1.1715281

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

High‐sensitivity photoconductor ``powder'' layers and ``sintered'' layers have been prepared in large‐area form, with most of the desirable characteristics of single crystals. The methods involved in the preparation of these layers are simple and avoid the difficulties involved in growing large‐area single crystals, or in producing large‐area photoconductors by evaporation in vacuum. Both types of layers can be made into photocells of any desired area, by providing suitable electrodes. At an illumination of 1 ft‐c, ratios of photo‐current to dark current as large as 106may be obtained for both types of layers. A two‐inch square cell made from either a powder or a sintered layer can pass an ampere for an illumination of a few foot candles. In addition to their ease of fabrication, the new layers also have advantages in the large increase in red sensitivity obtainable with cadmium sulfide, and in the ohmic character of sintered layers with silver‐paste electrodes.

ISSN:0034-6748    

DOI:10.1063/1.1715282

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An alternating‐gradient channel for containing relativistic electrons (7 Mev) is made by arranging sets of four permanent bar magnets along an evacuated tube. The resultant field from each set is calculated assuming point magnetic poles. Four configurations for the magnet sets are considered and the criteria for retaining and focusing the electron beam are established for each configuration by matrix analysis of the equations of motion of the electrons in the periodic magnetic fields. These equations relate the magnetic pole strengths, the set positions, and the electron energy ranges permissible for each case. The aperture of the configuration is indicated, and experimental results are given.

ISSN:0034-6748    

DOI:10.1063/1.1715283

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A low‐pressure laboratory liquefier having a capacity of 45 to 50 liters per hour is described. A combination of old and new features makes possible continuous operation without an attendant. Impurities such as water, carbon dioxide, and oil are eliminated automatically by reversing exchangers. The liquid nitrogen product flows directly from the rectifier to a large external storage vessel. The net power requirement is approximately 50 kilowatts.

ISSN:0034-6748    

DOI:10.1063/1.1715284

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A device is described which stabilizes the mean energy of the external beam from an FM cyclotron to better than 0.1 percent. This control is achieved by inspecting the end of the range of a sample of scattered particles, and then using this information to regulate the cyclotron magnet current. It is also used as an absolute instrument to measure the mean energy to 0.3 percent at the same time.

ISSN:0034-6748    

DOI:10.1063/1.1715285

出版商:AIP    

年代:1955

数据来源: AIP