We have studied on the possibility of a new method about the experimental determinations of the conductance at low pressures, using scattered light flow analogy.

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The vacuum gauge using the thermistor bead is described. We measured unbalanced current by wheatstone bridge circuit as is the case with the Pirani gauge. we investigated such effects as lead-wire diameter, character of thermistor bead, gauge diameter, and various gases on the sensitivity of the gauge. The gauge were fairly stable in the range 0.110⁴μg.

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The most sensitive leak detector is of the mass spectrometer type. But the one of this type is very expensive and not so easy to use and moreover helium as probe gas is difficult to obtain in our country. Here, the more simple and rather sensitive leak detector is obtained. This is the a.c. drived differential type pirani gauge with charcoal trap.
When aceton is used as the probe, the obtained maximum sensitivity is 10^-3lμ/sec.

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We have designed all equipments of the vacuum apparatus in the cyclotron which is now under reconstruction at Univ. of Kyoto and have been testing the leaks in many parts of it.
To have surmised that the speed in need of diffusion pump and operating pressure, we calculated the quantities of gases evolved from the surfaces of several commercial metals measuring the rate of pressure rise with the pumping gate closed.
The pitted face of a drown steel pipe showed at the largest quantity of evolved gases and the cold rolled surface of a brass showed at the smallest of it. Reducing to the equivalent amount of an air, the upper and the lower values of the evolved gases are estimated to be 2.2×10^-8mmHg, l·sec^-1 cm^-2 and 9.8×10^-10mmHg l sec^-1cm^-2 respectively at about 27°C
However, the effective speed of an oil diffusion pump and the effective conductance of a tube which connects between a pump and an equipment are found to be very smaller than the final speed and theoretical conductance in the initial condition respectively.

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We have been testing the vacuum leakage of many part in the cyclotron at the University of Kyoto with the detective system which uses a single ionisations gange as a measuring instrument at the five vacuum side and butane or propane gas as probing material.
We found an effect in which butane gas covering the leak point cut off the air from leaking in. The magnitude of the leak was then estimated to about 6.7×10^-4mm Hg l sec-1 of air.
Appling propane gas of high pressure over the leak, we observed the pressure-time relations of the leakage of which magnitude was estimated to 2.9×10^-6mmHg l sec^-1 of air.
Analysing this observation, we found that longer time was required for the displacement of the probe gas to a five vacuum side, and also such phenomena as follows;
a) the air in the leaking place was pressed by bing covered withe, high pressure gas over the leaking place, b) the probe gas in the leak remained for a time after removing the gas from the leaking place.

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A continuous distillation of diffusion pump oil was carried out in high vacuum with a glass apparatus which is characterized by watching the final pressure continuously in course of the operation.
The distillation rate of Di-2-ethyl-hexyl phthalate was 30 cc/hour at the final pressure 4×10^-6 mm Hg.

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A vacuum furnace using a molybdenum heater for use in pulling single crystals of germanium from a melt is described. It has a pulling rod with rotation two removable impurity adders a adjusting rod for crucible base and could be observed during the run through windows with shutters.
The vacuum system consisted of a 4″oil diffusion pump of the speed of 100l/sec and a 500l/min mechanical pump and the vacuum higher than 5×10^-5mmHg was maintained during operation

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A compression vacuum gauge is described that is capable of measuring pressures over the range from 3×10^-4mm of mercury to 1 atmosphere.
This gauge is designed reforming the idea by N.A. Fbresen. Requisite mercury is only 6070cc.

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