Fast beam chopper at SARAF accelerator via RF deflector before RFQ

A. Shor, D. Vartsky, V. Dangendorf, D. Bar, Y. Ben Aliz, D. Berkovits, M. Brandis, M. B. Goldberg, A. Grin, I. Mardor, I. Mor, L. Weissman

Research output: Contribution to journalReview articlepeer-review


We describe design and simulations of a fast beam chopper for the SARAF accelerator based on an RF deflector preceding the RFQ. The SARAF 176 MHz RFQ, takes a DC proton or deuteron beam and accelerates and bunches the beam to 1.5MeV/u and bunches of 0.3ns width (FWHM) every 5.5ns respectively. The deflector acts on the DC beam and sweeps away all but one of the pre-accelerated (pre)-bunches prior to the actual bunching and acceleration in the RFQ. Simulations were performed for a fast beam chopper, where several deflection voltage pulsing schemes have been investigated. The simulations show effective chopping with alternating positive and negative HV applied to the deflector with a fast HV switch, where the beam is transmitted to the RFQ during the cross-over of the rise(fall) of the HV switching. The simulations show that we can obtain efficient deflection of unwanted bunches, with 60% transmission efficiency for the desired bunch. The present design is for a chopper that will provide 0.3ns bunches with a repetition rate of ∼105bunches/sec. Plans for a fast chopper with higher repetition rates of ∼ 106 Hz are discussed.

Original languageEnglish
Article numberC06003
JournalJournal of Instrumentation
Issue number6
StatePublished - Jun 2012
Externally publishedYes


  • Accelerator Applications
  • Accelerator Subsystems and Technologies
  • Accelerator modeling and simulations (multi-particle dynamics
  • Instrumentation for neutron sources
  • single-particle dynamics)


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