DEVELOPMENT OF DISTRIBUTIVE PUMPING

The development of distributive pumping was carried out with the aim o f using it as a cheap and effective pumping system in the beam lines o f the existing 15 UD Pelletron and the planned booster. Non-evaporable getter (NEG) strip St 707 was laid in a test beam line with a modifie d, simpler and more economical design as compared to that of earlier w orks. An ultimate vacuum of 4 x 10(-10) torr was achieved using the di stributive pumping of NEG strip in addition to ion pump and titanium s ublimation pump. The activation of NEG strip even at 30 A reduced the rate of rise of pressure in the power off period by a factor of 0.004 in the system pumped by an ion pump. The rate of pressure rise was fur ther reduced by a factor of approximately 0.06, to a value of 7.2 x 10 (-9) torr h-1, with the incorporation of a titanium sublimation pump a nd activation of NEG at 60 A. The partial pressure measurement of vari ous gases was also carried out.