Timing measurements of the extraction kicker system at the Spallation Neutron Source

The Spallation Neutron Source (SNS) extraction kicker system is a high power 60 hertz pulsed power system.¹ The system consists of fourteen identical modulators, each driving a magnet to extract a proton beam from the accumulator ring through the beam transfer line to the target. The kickers are required to reach maximum magnetic flux density during a 200-250 ns beam gap in the accumulator ring. Timing variations in the modulator and/or trigger system could cause firing outside of the beam gap causing beam loss resulting in residual activation and possible equipment damage. Each modulator is a Blumlein Pulse Forming Network (BPFN) with a fast high current switching thyratron and low inductance capacitor banks. This paper describes measurements made to characterize the jitter and drift associated with the trigger system, thyratron and BPFN. Furthermore, the effect of firing asynchronously to the line voltage on jitter of the thyratron trigger system is discussed.