| Paper |
Title |
Page |
| MOPC056 |
Challenges for Beams in an ERL Extension to CESR
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190 |
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- G. Hoffstaetter, I. V. Bazarov, S. A. Belomestnykh, M. G. Billing, G. W. Codner, J. A. Crittenden, B. M. Dunham, M. P. Ehrlichman, M. J. Forster, S. Greenwald, V. O. Kostroun, Y. Li, M. Liepe, C. E. Mayes, H. Padamsee, S. B. Peck, D. H. Rice, D. Sagan, Ch. Spethmann, A. Temnykh, M. Tigner, Y. Xie
CLASSE, Ithaca
- D. H. Bilderback, K. Finkelstein, S. M. Gruner
CHESS, Ithaca, New York
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Cornell University is planning to build an Energy-Recovery Linac (ERL) X-ray facility. In this ERL design, a 5 GeV superconducting linear accelerator extends the CESR ring. Currently CESR is used for the Cornell High Energy Synchrotron Source (CHESS). The very small electron-beam emittances would produce an x-ray source that is significantly better than any existing storage-ring light source. However, providing, preserving, and decelerating a beam with such small emittances has many issues. We describe our considerations for challenges such as optics, space charge, dark current, coupler kick, ion accumulation, electron cloud, intra beam scattering, gas scattering, radiation shielding, wake fields including the CSR wake, and beam stabilization.
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| MOPC064 |
Beam Losses Due to Intra-Beam and Residual Gas Scattering for Cornell's Energy Recovery Linac
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214 |
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- A. Temnykh
Cornell University, Department of Physics, Ithaca, New York
- M. P. Ehrlichman, G. Hoffstaetter
CLASSE, Ithaca
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In this paper we analyze particle loss rates in Cornell's x-ray Energy Recovery Linac. Because of the small beam emittances and high beam intensity, intra-beam scattering (IBS) can be a source of significant particles loss in the horizontal plane. It will result in radiation doses which should be carefully examined for adequate radiation protection. Additionally, scattering on the residual gas (RGS) causes particle losses in the vertical plane. With Mote-Carlo type simulations of the scattering processes and transport matrixes for particle-trajectory propagation we found the beam loss distribution along ERL. It indicated that 99% of the total beam loss will be due to IBS. However, the RGS contribution can not be ignored because it dominates scattering in the vertical plane causing IDs irradiation and damage. For both (IBS and RGS) processes the highest beam losses will occur at the end of deacceleration due to adiabatic anti-damping causing traverse betatron amplitudes to increase. These beamlosses can be consentrated in collimation sections. Knowing RGS beam loss rates at the ID locations, we estimate the ID’s life time and suggest a radiation protection scheme.
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| TUPP040 |
Intra Beam Scattering in Linear Accelerators, Especially ERLs
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1631 |
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- G. Hoffstaetter, M. P. Ehrlichman, A. Temnykh
CLASSE, Ithaca
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The theories of beam loss and emittance growth by Touschek and Intra Beam Scattering have been formulated for beams in storage rings. It is there that these effects have hitherto been important because of their large currents. However, there are linear accelerators where these effects become important when considering loss rates and radiation damage. Prime examples are high current Energy Recovery Linacs (ERLs), managing these scattering effects can become challenging, and not only because of the large current, but also because the deceleration of the spent beam increases relative energy spread and transverse oscillation amplitudes. In this paper we describe two ways of simulating particle loss by these scattering affects, both implemented in BMAD. One that yields the places where scattering occurs, and another that yields loss rates along the chamber walls. BMAD includes nonlinear beam dynamics, wake effects, and more, which allows a rather complete propagation of scattered particle. For the example of the ERL x-ray facility that Cornell plans to build, we demonstrate that these capabilities are very important for designing a functional radiation protection system.
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