Rapid Cycling Synchrotrons and Accumulator Rings for High-Intensity Hadron Beams

Abstract

Boosted by the needs in high-energy physics and nuclear physics and also multidisciplinary applications, high-intensity proton synchrotrons and accumulator rings have been developed quickly around the world over the last 30 years. New projects and plans are proposed with even higher beam power. The proton beam power has increased from less than 10 kW in the 1970s to about 1 MW level today, and the required beam power in the coming decade is a few MW. This article reviews the achievements in designing and constructing rapid cycling synchrotrons (RCSs) and accumulator rings (ARs) and the future development trends, principally on proton beams but also including heavy ion beams. It presents the evolution of RCS and AR machines, today's design philosophy, relevant accelerator physics, and also state-of-the-art accelerator technology.

Integrable RCS as a proposed replacement for Fermilab Booster

“…If a second harmonic RF cavity is used during injection, a more uniform charge density can be achieved while maintaining this longitudinal emittance [19,20]. To minimize power losses, the lattice magnets will follow a sinusoidal ramp curve [11]. A corrector circuit will flatten the sinusoidal ramp curve during injection, so that the injection energy consistently matches the lattice energy.…”

“…The iRCS should incorporate the innovations in RCS design that have been developed after the Fermilab Booster [11]. Periodicity and bounded beta functions increase the dynamic aperture.…”

“…To minimize power losses, the lattice magnets will follow a sinusoidal ramp curve [11]. A corrector circuit will flatten the sinusoidal ramp curve during injection, so that the injection energy consistently matches the lattice energy.…”

“…The Laslett tune-spread is given by where N is the number of particles, r 0 is the classical electron radius, N is the normalized transverse emittance, λ(z) is the local charge density at position z, and F is a transverse form factor [4]. An integrable RCS could manage a high Laslett tune-spread without a costly increase in aperture [11]. Detailed simulations of space-charge dominated beams in integrable lattices is an ongoing work [2,12], and the ultimate limitation in Laslett tune-spread is not fully determined.…”

“…Figure 1 shows one of several siting options for an iRCS and it does not limit the circumference. Excess circumference can raise the costs of the RF system by increasing the revolution frequency [11]. The iRCS ramp rate indirectly affects the 120 GeV beam power by reducing the Main Injector fill time.…”