Fast-switching magnet serving a spallation-driven ultracold neutron source

F Fischer,W Klassen,E Pierre,T Hayamizu,S Sidhu,S Hansen-Romu,R Mammei,S Ahmed,R Picker,B Franke,E Korkmaz,B Bell,T Lindner,F Kuchler,Takamasa Momose ,Michael Gericke ,Yutaka Watanabe ,Michael Barnes ,Eric K Miller ,W T H Van Oers ,W D Ramsay ,David P.h Jones ,Charles A Davis ,Sean Vanbergen ,Michael E Hahn ,Kirk W Madison ,J W Martin ,Mala Das ,Yi‐Nong Rao ,Emily Altiere ,Chris Bidinosti ,Μ Lang ,W R Rawnsley ,L L Kurchaninov ,R Matsumiya,L Rebenitsch,D Yosifov,T Andalib,K Katsika,L Lee,T Kikawa,Y Bylinsky,B Jamieson,W Schreyer,K Hatanaka,S Kawasaki,A Konaka,P Giampa,J Mammei,J Chak

doi:10.1103/physrevaccelbeams.22.102401

Abstract

A fast-switching, high-repetition-rate magnet and power supply have been developed for and operated at TRIUMF, to deliver a proton beam to the new ultracold neutron (UCN) facility. The facility possesses unique operational requirements: a time-averaged beam current of 40~$\mu$A with the ability to switch the beam on or off for several minutes. These requirements are in conflict with the typical operation mode of the TRIUMF cyclotron which delivers nearly continuous beam to multiple users. To enable the creation of the UCN facility, a beam-sharing arrangement with another facility was made. The beam sharing is accomplished by the fast-switching (kicker) magnet which is ramped in 50~$\mu$s to a current of 193~A, held there for approximately 1~ms, then ramped down in the same short period of time. This achieves a 12~mrad deflection which is sufficient to switch the proton beam between the two facilities. The kicker magnet relies on a high-current, low-inductance coil connected to a fast-switching power supply that is based on insulated-gate bipolar transistors (IGBTs). The design and performance of the kicker magnet system and initial beam delivery results are reported.

Highlights

IntroductionThe TRIUMF cyclotron delivers a nearly continuous proton beam with a pulse frequency of 1.126 kHz. The cyclotron accelerates H− ions, using stripper foils to deliver protons at various radii (energies) to up to four beamlines (numbered 1, 2A, 2C, and 4) simultaneously
MOTIVATIONThe TRIUMF cyclotron delivers a nearly continuous proton beam with a pulse frequency of 1.126 kHz
Coexistence and simultaneous operation of the new ultracold neutron (UCN) facility is only achievable due to the fast-switching kicker magnet which switches between the facilities

Summary

Introduction

The TRIUMF cyclotron delivers a nearly continuous proton beam with a pulse frequency of 1.126 kHz. The cyclotron accelerates H− ions, using stripper foils to deliver protons at various radii (energies) to up to four beamlines (numbered 1, 2A, 2C, and 4) simultaneously. A new ultracold neutron (UCN) source was developed at TRIUMF, with the initial planning beginning in 2008. The UCN source requires a minute-long beam-pulse structure. Accommodating an additional facility which depends on intermittent beam delivery at variable intensity required the ability to share the beam. This was implemented in beamline 1 at TRIUMF and a beam-sharing arrangement made with the meson-production facilities. Coexistence and simultaneous operation of the new UCN facility is only achievable due to the fast-switching kicker magnet which switches between the facilities

Methods

Results

Conclusion