ISSN:0034-6748    

DOI:10.1063/1.1751546

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

A short description is given of an expansion liquefier which yields a supply of liquid helium in a Dewar vessel and is very economical in liquid hydrogen.

ISSN:0034-6748    

DOI:10.1063/1.1751547

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

Extending work by F. K. Harris, we show how to produce a highly uniform magnetic field in a rectangular box long compared with its cross section, by using a pair of rectangular coils placed on opposite sides of the box. If the width of each coil is 3½times the distance between them, the region in which the field deviates less than one percent from the value at the center is about nine times larger than that obtained with previous coils having other width‐distance ratios. The use of square wire‐bundlles causes the main correction terms depending on finite cross section to vanish. The homogeneity achieved compares favorably with that obtainable by Helmholtz coils.

ISSN:0034-6748    

DOI:10.1063/1.1751548

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

In the first part an account is given of the methods, tried in the Laboratory of Physical Chemistry, Upsala, for measuring the speed of the ultracentrifuge. The methods can be classified according to the nature of the primary indicator, which may be of optical or of electrical design. In the first case (optical methods) the stroboscope and a photo‐cell device are considered. In the second case an electrical indicator of the following type has been designed and constructed. A part of the rotor shaft has been magnetized in a radial direction and a stator is mounted in the centrifuge casing. The frequency or the e.m.f. of the power produced by the indicating generator is measured by means of different methods. The oscillograph, different resonance circuits and bridge circuits have been considered. In the second part a description is given of a device for the automatic regulation of the speed of the ultracentrifuge. The frequency from the indicating generator is connected to a bridge. The output voltage from this is applied to a phase reversing bridge, which controls the oil supply to the centrifuge turbines by means of relays.

ISSN:0034-6748    

DOI:10.1063/1.1751549

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751550

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751553

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751556

出版商:AIP    

年代:1939

数据来源: AIP