Alinear Current - Frequency Converter for Ion Pump Current Readout

In simple vacuum systems employing a' single ion pump, it is common to use the linear pump current pressure relationship to advantage, eliminating the need for a separate vacuum gauge by reading the ion pump power supply current. In large systems it becomes prohibitively expensive to install a power supply for each pump and in such systems one or more central supplies are usually used with a distribution scheme for the high voltage. Then, however, the power supply current is the sum of the currents of the pumps connected to the supply and one loses the "gauge" facility unless he is willing to measure currents at the high voltage end of the pump. This note describes a simple way of doing this at a reasonable cost.