摘要:

A Wheatstone‐bridge arrangement of capillary tubes carrying a flow of inert gas is described, with which the resistance to flow of a capillary tube serving as a thermometer may be measured. The resistance is shown to be proportional to the productT&eegr;, for constant mass rates of flow in the viscous regime. Gas‐viscosity thermometers have relatively open and linear scales, and are usable over wide temperature ranges. With helium gas, for example, the productT&eegr;varies strongly and smoothly with temperature from below 1° to above 1500°K and probably much farther. Experimental tests of Al2O3capillary thermometers in a high temperature furnace are reported. Some of the thermometers were reasonably stable at 1788°K.

ISSN:0034-6748    

DOI:10.1063/1.1717135

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A variable‐area water rheostat has been applied to the problem of current control in electric arc and plasma generating equipment. Resistance between 0.5 and 30 ohms can be obtained by adjusting the height of circulating water which surrounds pairs of fixed vertical aluminum plates. The electrolyte is ordinary city water which is circulated through the tank and discharged. No special filtering, pumping, or other treatment is used. The unit is located in the open air outside the laboratory and all control functions are operated from a remote switching panel. The unit has been operated using a maximum of 125 amp at 400 v dc and 1000 amp at 230 v dc.

ISSN:0034-6748    

DOI:10.1063/1.1717150

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Two encapsulated germanium thermometers have been calibrated and tested between 1.4° and 4.2°K. Within the precision of the measurements (±0.4 millidegree) no change in their calibration was found after cycling to room temperature or after temporary removal from the measuring apparatus. In this respect, the germanium thermometers were considerably better than carbon thermometers. For comparison a carbon thermometer was encapsulated and found to undergo unpredictable changes corresponding to several millidegrees under similar circumstances.

ISSN:0034-6748    

DOI:10.1063/1.1717168

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An arrangement is described which allows potential‐time measurements in galvanostatic pulse techniques to be performed 40–80 m&mgr;sec after initiation of the pulse.

ISSN:0034-6748    

DOI:10.1063/1.1717132

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

This paper describes the design and construction of a microwave separator for high energy particle beams, following the original ideas of Panofsky and Wenzel. We used a TM012rectangular cavity with aQof 15 000 and a maximum power dissipation of 1.3 Mw (megawatts). With this we could deflect electrons of 150 Mev/c momentum through ¾ in. at the final focus of our analyzing magnet. The available aperture is so small that the technique is not immediately useful, but we anticipate that it may become so at higher energies, when other methods of beam separation become unfeasible.

ISSN:0034-6748    

DOI:10.1063/1.1717133

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Ions are injected into an insulating liquid and pumped into a collector, which assumes a high potential. Results of a theoretical treatment of this arrangement are compared with experimental evidence. While the generator has low energy conversion efficiency, it possesses a number of compensating advantages.

ISSN:0034-6748    

DOI:10.1063/1.1717134

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A formula for the signal‐to‐noise ratio of a maser spectrometer is derived by considering it as a special case of a cavity spectrometer. This formula is consistent with evaluations made by previous authors but is more convenient for comparison with an absorption cavity spectrometer. In applications where high resolution is not a requirement, the pressure and power level in an absorption spectrometer may be made very large so that its sensitivity can be superior to that of the maser. However, if it is operated to obtain the highest possible resolution, its sensitivity may or may not be superior to that of the maser, depending upon the frequency and upon other conditions. In the situation of greatest interest, in which the linear dimensions of the cavity are scaled in proportion to the wavelength and in which it is sufficiently large to make the effect of collisions between the molecules and the walls negligible, it is shown that the sensitivity of the maser relative to the absorption spectrometer varies inversely with the frequency. The theory is illustrated by calculations pertaining to spectrometers designed for the ND3inversion spectrum at 1500 Mc. From these calculations it can be inferred that, with the best available techniques, the two instruments would have about equal sensitivity in the region of 1500 to 2000 Mc, while at lower frequencies the maser would have higher sensitivity and the absorption spectrometer would have higher sensitivity at higher frequencies.

ISSN:0034-6748    

DOI:10.1063/1.1717136

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A scheme is described for locking the frequency of a marginal oscillator rf spectrometer to that of an external standard. This makes it convenient to use such a spectrometer for high resolution NMR work.

ISSN:0034-6748    

DOI:10.1063/1.1717137

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A technique has been developed for making Gouy type measurements of magnetic susceptibility in high transient magnetic fields. The magnetic force on the sample travels as a stress wave through the apparatus assembly and excites a voltage on two piezoelectric crystals which are the active elements of the transducer. The apparatus has a small risetime and high response. Typical experimental difficulties are described.

ISSN:0034-6748    

DOI:10.1063/1.1717138

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A hydrostatic high pressure apparatus capable of achieving 18 kilobars at room temperature, 14.1 kilobars at 77°K, and limited in pressure at lower temperatures only by the freezing of helium is described. A number of techniques facilitating construction, operation, and repair are described. An experimental pressure vessel and cryostat for optical studies to 16 kilobars in the temperature range from 370° to approximately 60°K are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1717139

出版商:AIP    

年代:1961

数据来源: AIP