摘要:

The recent development of the helium isotope refrigerator, using mixtures of the two isotopes of helium, is probably the most important step forward in the technique of producing low temperatures since adiabatic demagnetization. This article attempts to describe the special properties of3He-4He mixtures, and to show how these properties are used to produce refrigeration below 0.1 °K. Design details of actual refrigerators are given, and the direction of future improvements is suggested by a consideration of simple models of the various refrigerator components.

ISSN:0010-7514    

DOI:10.1080/00107516808202172

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A brief discussion is given of the need for pressures below 10−9torr and of the developments which began in 1950 and made possible the reliable measurement of pressures as low as 10−12torr. The greatest technical change in passing from high to ultra-high vacua is in materials since all components exposed to the vacuum have to be baked to at least 300 °c. All of the pumps, gauges, mass spectrometers, taps and other components described in this article must fulfil this requirement. Examples are taken from two small ultra-high vacuum systems in use at Southampton, one is a getter-ion pumped system in stainless steel, the other a mercury-diffusion pumped system in glass.

ISSN:0010-7514    

DOI:10.1080/00107516808202173

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808202174

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This article explaiins the general nature of the large and often disastrous waves known as tsunamis. The hydrodynamical behaviour of deep-water waves arising from disturbances on the sea-bed is discussed, and an account is given of methods of measurement and of some recent observations.

ISSN:0010-7514    

DOI:10.1080/00107516808202175

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Plasma phenomena in the solid state combine the essential characteristics of the gaseous plasma with those of the solid state such as band structure, degeneracy and anisotropy, and lead to new and interesting types of behaviour.

ISSN:0010-7514    

DOI:10.1080/00107516808202176

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808202177

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor