Digital Control O F Rectifier Firing Angles for the Zero Gradient Synchrotron

The hea r t of the new control s y s t e m for the ZGSring magnet power supply i s a counter that countsf r o m 0 to 3600 each voltage cycle of the main genera-to r .synchronized with the generator voltage wave by aphaselock feedback loop.number i n the counter with the des i red angle fo r f i r ingeach of the 12 rectif ier phases.i s generated and applied to the control gr ids of theappropriate mercu ry vapor rec t i f ie rs .ari thmetic adder circuits upclate the des i red f ir ingangles for each of the 1 2 phases in response to com-mands f r o m the ZGS p rogrammer and in response to.feedback slgnals f r o m beam spill monitors and f r o m Bpickup coils on the ring magnet.a r i thmet ic adders and se lec tors provide individual ad-justment of each phase in order to reduce low f r e -quency ripple.l o o , and 150-cycle ripple on the r ing magnet field onflattop and on porches, has provided fas t action tope rmi t spil l control when the RF accelerat ing cavityis off, and has provided stable operation in full rectifyf o r the accelerat ing p a r t of the ZGS cycle.This provides an e lec t r ica l degree scale that i s Digital gates compare the At eauality, a pulse