β Scribed by D Andrew
No coin nor oath required. For personal study only.
The design and operating technique for an apparatus for the measurement of pump speeds of sputter ion pumps in the range 10 to 100 litres/sec is described. In spite of the precautions taken a large variation in the measured value is observed. The speed of a sputter ion pump is found to depend both on the initial condition of the pump and the operating condit.'o~s during the measurement. It is found experimentally that operating the pump at high pressures of argon is a practical method for obtaining a repeatable pump condition prior to measurement of the pump speed. The subsequent pump speed observed for nitrogen flow gas is found to fall as a function of the quantity of gas pumped. It appears necessary to further investigate this phenomenon using a partial pressure analyser. Alternative known methods of evaluation of pump performance are discussed but are seen to suffer similar difPculties.
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