Order-of-Magnitude Beam Current Improvement in Compact Cyclotrons

Abstract

There is great need for high intensity proton beams from compact particle accelerators in particle physics, medical isotope production, and materials-and energy-research. To this end, the DAEδALUS/IsoDAR collaboration is developing a compact isochronous cyclotron that will be able to deliver 10 mA of protons-an order of magnitude higher than on-market compact cyclotrons and a factor four higher than research machines. For the first time, vortex motion is incorporated in the design of a cyclotron, which is key to reaching high extracted beam current. We present highfidelity simulations of the acceleration of a 5 mA H + 2 beam (equivalent to 10 mA of protons) in this cyclotron, using the particle-in-cell code OPAL, demonstrating the feasibility of constructing this machine. The simulations are based on the latest cyclotron design and through them, we show that sufficient turn separation between the (N − 1) th and N th turn can be achieved even with initially mismatched beams by careful placement of collimators to scrape away halo particles before the beam energy has reached 1.5 MeV/amu. We describe in detail the process for placement of electrostatic extraction channels. Beam losses on the septa of these channels stay below 50 W with beam quality sufficient for transport to the target. Furthermore, we present an uncertainty quantification of select beam input parameters using machine learning, showing the robustness of the design.

IsoDAR@Yemilab: A Report on the Technology, Capabilities, and Deployment

“…9, as the beam circulates, the combination of space charge effects and external focusing forces induce bunches to curl tightly in phase-space. This prevents the massive losses that some accelerator physicists had predicted would occur on the extraction septum, due to radial overlap of bunches in adjacent turns close to extraction from the cyclotron [26,29]. The formation of the stable vortices does push a fraction of the bunch into larger "halo" orbits, but these can be removed using carefully-placed collimators, all located in the central region where the beam energy is below the Coulomb barrier so no activation or neutrons are produced.…”

Snowmass Neutrino Frontier Report

“…Cyclotrons represent another novel artificial source of neutrinos [118,119]. The IsoDAR experiment [120] will utilize a high power (600 kW) cyclotron to produce a 60 MeV proton beam [121]. Beam interactions with a beryllium target create an intense source of neutrons which subsequently enter a surrounding 7 Li sleeve, thermalize, and then capture on 7 Li to create the high-Q beta-decay isotope 8 Li.…”

Input Beam Matching and Beam Dynamics Design Optimization of the IsoDAR RFQ using Statistical and Machine Learning Techniques

“…This accelerator (described in Refs. [15,17,18]) accelerates H + 2 instead of protons and uses a novel RFQ direct injection method [15,19], in which the beam is aggressively pre-bunched in an RFQ that is embedded axially in the cyclotron yoke and brought very close to the cyclotron median plane. Because of the high beam current, necessarily small diameter (as little yoke iron as possible must be removed), and the difficult matching of the RFQ output to the cyclotron acceptance, we have initiated this study to accurately predict the sensitivity of the RFQ, the output beam parameters, and to optimize the RFQ design beyond the current baseline.…”