Transverse beam profiles are observed to broaden with increasing intensity in the Proton Storage Ring at the Los Alamos Neutron Scattering Center. Measured profiles are simulated with an H 2 injection model that includes a 2D particle-in-cell space charge calculation. Inclusion of space charge effects in the simulation improves the agreement between the experimentally observed profiles and the calculated profiles. The comparisons are made for a range of injected intensities.
Uncontrolled beam losses due to space-charge-induced halo generation are a concern in high intensity rings, which are characterized by high beam intensities and low uncontrolled beam loss requirements. It is therefore important to investigate the dynamics of space charge in high intensity rings. We report here the results of extensive calculations using a particle-tracking approach with a self-consistent particle-in-cell model and alternatively with a particle core model. We find that the inclusion of space charge forces provides agreement between calculated and experimentally observed beam profile shapes in the high intensity proton storage ring. We also confirm computationally the extension to rings of the accepted dynamics of halo generation with rms beam mismatch exciting the parametric resonance. In addition, we propose a new two-stage mechanism for halo production in rings in which space-chargedriven lattice resonances generate beam mismatch that excites the parametric resonance. Because of its dependence on lattice resonances, this mechanism is peculiar to rings and is capable of generating halo even from initially matched beams. It is also very sensitive to the operating point in tune space, as we show in the results of a vertical tune scan simulating injection into the Spallation Neutron Source accumulator ring. Our results extend and enhance the understanding of fundamental space charge physics, which has been developed for linear accelerators, to rings.
The Spallation Neutron Source (SNS) project is a collaboration among Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge National Laboratories. The Linac, which injects beam into an accumulator ring, is comprised of both normal and superconducting rf (SRF) accelerating structures. Two room-temperature rf structures, a 402.5-MHz drift-tube linac (DTL) and an 805-MHz coupled-cavity linac (CCL), accelerate an H-minus beam from 2.5 MeV to 186 MeV. The SRF linac accelerates the beam to 1 GeV through 81 elliptical, multicell niobium cavities. This paper reviews the linac physics design and its expected beam dynamics performance.
Tenreiro, C (Tenreiro, Claudio). Univ Talca, Talca, Chile.The Korea Rare Isotope Accelerator, currently referred to as KoRIA, is briefly presented. The KoRIA facility is aimed to enable cutting-edge sciences in a wide range of fields. It consists of a 70 kW isotope separator on-line (ISOL) facility driven by a 70 MeV, 1 mA proton cyclotron and a 400 kW in-flight fragmentation (IFF) facility. The ISOL facility uses a superconducting (SC) linac for post-acceleration of rare isotopes up to about 18 MeV/u, while the SC linac of IFF facility is capable of accelerating uranium beams up to 200 MeV/u, 8 p mu A and proton beams up to 600 MeV, 660 mu A. Overall features of the KoRIA facility are presented with a focus on the accelerator design
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