Design, development, and construction of SNS extraction fast kicker system

The SNS accumulator ring extraction fast-kicker system was design, developed, and prototype tested at the Brookhaven National Laboratory. Its construction has just begun. The system is for one-turn fast extraction ejecting proton beam from the ring into the extraction septum gap and further deflecting into the ring-to-target beam transport line. The system consists of fourteen high-voltage modulators, their local control and auxiliary systems, and fourteen window frame magnet sections. High-voltage transmission cables will be used for pulse transmission from modulators to their corresponding magnet sections. The high-voltage and high-current pulse has a rise time about 200 ns, a pulse duration about 700 ns, and a current amplitude above 2500 Amp per modulator. The modulator design features a Blumlein Pulse-Forming-Network with ultra-low inductance high energy storage pulsed capacitors, an ultra-fast high-power hollow anode thyratron, a parallel resistor stack for low beam-impedance termination, and a saturable inductor stack for beam current isolation and pulse rise time sharpening. This design is driven by the considerations of low beam loss, high maintainability and reliability. All high voltage modulators will be placed outside the ring tunnel and the system is immune to one-kicker failure. In addition, the enlarged magnet aperture can accept all four working points. The design concept has been successfully proven by the prototype test. The techniques, considerations, and other related issues of the system design, development and construction are discussed in this paper.