Precision Integrator for Ion Beams

The integrator consists of a circuit which operates relays to turn off data‐storage devices, timers, etc., when the charge conducted by an ion beam reaches a specified quantity. A vibrating‐reed electrometer (without feedback) senses when the potential drop across a capacitor into which the beam current flows becomes equal to the potential of several standard cells in series. Errors in sensing the potential are less than 0.001%, and the over‐all time delay of the relay operation is about 15 msec. The major sources of error are associated with soakage and changes in capacitance with temperature, less than 0.05% and about −0.01% per °C, respectively. It should be feasible to attain a considerable reduction in all the errors of integration caused by these known sources of error.