Abstract
A large mercury diffusion pump with glass casing was made to construct the set to calibrate the standard ionization gauges against a standard Mc Leod gauge.
The inside diameter of the pump casing is 80mm and the top jet clearance ared is 37.7cm2. The jet assembly is made of mied steel.
For example, the maximum throughput, pumping speed and speed and critical back pressure (Q=O) at 500 watts heater input are 730 μHg·l/sec, 145l/sec and 0.5 mmHg respectively.
The performance is not inferior to that of an oil diffusion pump at comparable conditions.
