New Methods for Stabilizing Dee Voltage and Beam R.F. Phase

A short term peak to peak Dee voltage stability of 10-4 is obtained by introducing a "ripple memory" in the voltage regulation system. The ripple memory consists of a shift register storing the drive signal needed to cancel the ripple. The stored signal is continuously updated. It is shown that the memory can be added to existing systems, reducing ripple by up to two orders of magnitude. A beam phase detection system which can be used at nanoampÿre beam currents is described. The beam bursts are detected by high input impedance pick-up probes. Synchronous detection of a low frequency beam intensity modulation is used to eliminate any Dee voltage interference. Theoretical and experimental values of the output noise level are given.