High power high voltage bias-T units capable of delivering up to 100 kW CW RF power at 176 MHz and up to 4 kV DC were developed at the Soreq Nuclear Research Center for the Soreq Applied Research Accelerator Facility linac. Two separate bias-T units with different requirements were designed for the radio frequency quadrupole couplers and the half wave resonator couplers. The purpose of this bias-T is to prevent multipacting phenomena by application of a high voltage DC bias to inner conductors of RF couplers. Underlying design principles, indigenous development, and successful off-line and on-line tests results are presented.

A fast chopper system has been developed for single-bunch selection for Phase I of the Soreq Applied Research Accelerator Facility (SARAF) in Israel. Further upgrade of the fast chopper system has improved its performance by enabling single-bunch selection for protons and deuterons at a repetition rate up to 220 kHz, with bunch transmission of up to 65% and with neighboring bunch contamination of less than 15%. The upgrade included (1) the redesign of the chopper deflection plates to minimize the electric-field asymmetry and provide more effective single-bunch selection, (2) a new trigger system with better trigger time resolution and better control capabilities, (3) an upgrade of the chopper electronics to increase the repetition rate, (4) the design of the chopper machine protection system, and (5) a general upgrade of the chopper concept to allow for operation in fast and slow modes. The implemented upgrades and the performance of the upgraded system are described. In addition, examples of the first experiments using the neutron time-of-flight (TOF) technique are presented. A fast neutron TOF facility, based on the upgraded fast chopper, is planned for SARAF Phase II. The high neutron flux at SARAF Phase II combined with the upgraded fast chopper system will make SARAF competitive with other advanced neutron research facilities.

The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Research Accelerator Facility (SARAF) injector and must be able to operate at RF powers up to 190 kW continuous wave and transport 5 mA proton and deuteron beams. The SARAF Phase I RFQ is planned for use in Phase II. The period between the termination of Phase I and the installation of Phase II provided an opportunity to introduce RFQ improvements to fully meet the Phase II requirements. These upgrades and improvements are presented in this report together with the results of the recent conditioning campaigns.

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The authors of this study developed a high-power inductive coupler with a high-voltage DC blocker that is capable of delivering up to 100 kW of CW RF power at 176 MHz and 4 kV DC. The high-power indictive coupler was developed at the Soreq Nuclear Research Center for the radio-frequency quadrupole of the Soreq Applied Research Accelerator Facility. The purpose of the DC blocker is to enable the application of high-voltage DC bias to the inner conductors of the couplers in order to prevent the multipacting phenomena. A new, mechanically and thermally improved, version of the RF coupler is designed and implemented in conjunction with the DC blocker. The underlying design principles, indigenous development, and results of tests of the coupler are presented here.