Soreq NRC, Yavne
The SARAF front end is composed of a proton/deuteron ECR ion source and a LEBT to match the beam to a 4-rod RFQ. The LEBT is consisting of an analyzing magnet, an aperture, three magnetic solenoid lenses and a diagnostic system. The typical operation vacuum, downstream the analyzing magnet, is of the order of 10-6 mbar at 5 mA analyzed beam current. In the emittance measurement we identify a beam of secondary-species particles, differently affected by the solenoid and so arriving with a different phase-space profile at the emittance detector. The secondary beam is the result of a charge exchange interaction in which an ion interacts with residual gasses in the beam line, most likely hydrogen gas coming from the ion source, and become neutral. For 20 keV protons colliding with H2 the calculated ion neutralization rate is 1%/m/10-6 mbar. Since the neutral portion of the beam is not affected by the magnetic focusing / steering elements, a none concentric neural and ion beams in the phase-space is a measure of mistuned beam or misalign magnets. These effects were proved and followed by beam dynamics simulation and are used to match the beam to the RFQ.
Soreq NRC, Yavne
NTG Neue Technologien GmbH & Co KG, Gelnhausen
RI Research Instruments GmbH, Bergisch Gladbach
Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is currently being commissioned at Soreq NRC [1]. According to the Phase I design, SARAF should yield 2 mA proton and deuteron beams at energies up to 4 and 5 MeV, respectively. The status of the main Phase I components is reported. We further present beam commissioning results, which include acceleration of a 1 mA CW proton beam up to 3 MeV. Further improvements in the facility in order to achieve the desired performance are discussed.
Soreq NRC, Yavne
Design of ion linacs with ion currents of several milli-amps necessitates detailed simulations of beam loss. At high intensities, even a small amount of beam loss can result in significant radio-activation of the linac components. Particle loss can result from longitudinal tails created in the bunching and pre-accelerating process, whereas strong transverse focusing and collimation limit the development of a transverse tail. In modern RF ion linacs, bunching and pre-acceleration take place in a radio frequency quadrupole (RFQ). We present a new approach for beam loss calculations that places emphasis on the tails of the particle distributions. This scheme is used for simulating the SARAF proton/deuteron linac, a 176 MHz complex designed to operate in CW mode at 4 mA beam current. We describe implementation of a RFQ accelerating element in the GPT 3D simulation code. We discuss our scheme for highlighting the tails of the particle distributions generated by the RFQ. These distributions are used as input to simulations of the RF superconducting linac, where subsequent particle loss is calculated. This technique allows us to increase beam loss statistics by a significant factor.