BNL, Upton, New York, USA
The RHIC ion (polarized proton) beam intensity has increased to 4x (1.1x) of the original design specifications. In 2013 proton beam currents overcame the eddy current reduction design features in the RHIC beam abort system kicker magnets causing ferrite heating and resulting in a reduction of the kicker strength. In 2014, the abort kicker ferrites were changed, the eddy current reduction design was upgraded, and an active ferrite cooling loop installed to prevent heating. For ions the beam dump vacuum window was changed from stainless steel to a titanium alloy and the adjacent beam diffuser block carbon material was changed to allow for higher ion intensities. A thicker beam pipe was installed to prevent secondaries from quenching the adjacent superconducting quadrupole. With these upgrades there is at least a factor 2 of safety margin for the demonstrated intensities to date. For a further increase in the intensity for RHIC and eRHIC we evaluate upgrade options for the beam abort system.
FRIB, East Lansing, Michigan, USA
NSCL, East Lansing, Michigan, USA
The cascade arc discharge, also called "plasma window", was suggested to be used as an interface to provide an effective separation between atmosphere and vacuum [1]. As suggested by Thieberger and Hershcovitch at Facility for Rare Isotope Beams (FRIB) workshop in 2009, helium plasma window offers an alternative to a large pumping system used in helium gas charge stripper for high intensity heavy ion beam accelerator facilities [2]. In this report, we present the recent progress on the development of helium plasma window with both 6mm and 10 mm diameter apparatus [3]. The size dependent sealing performance of helium plasma window has been investigated. Various diagnostics tools have been developed to improve our understanding of underlying physics. Over 140 hours continuous unattended operation of helium plasma window in recirculating gas system has been achieved, which suggests our system to be a feasible charge stripper solution for heavy ion beam accelerators. We also discuss anticipated future developments of plasma window.
[1] A. Hershcovitch, Phys. Plasma 5, 2130 (1998).
[2] H. Imao, et al., Phys. Rev. ST Accel. Beams 15, 123501 (2012).
[3] A. LaJoie, J. Gao and F. Marti, IEEE Transactions on Plasma Science (2019)
FRIB, East Lansing, Michigan, USA
Facilities for rare isotope beams provide tools for nuclear science research and tools for applications ranging from fundamental nuclear structure and dynamics to societal benefits in medicine, energy, material sciences and national security. State-of-the-art rare isotope facilities can be based on an isotope separation on-line (ISOL) approach using mostly high-power proton beams striking a thick target where the isotopes are produced in the target, or an in-flight fragment separation (IF) approach using high-power heavy ion beams striking upon a thinner target where the isotopes continue out of the target followed by fragment separation. This tutorial class introduces high power hadron accelerators as driver machines for rare isotope production, summarizing the key design philosophy, physical and technical challenges, and current world-wide development status. As an example, the Facility for Rare Isotope Beams (FRIB) project is used to illustrate the process of establishing such facilities.
