| Paper | Title | Page |
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| THPC045 | Beam Uniformization System Using Multipole Magnets at the JAEA AVF Cyclotron | 3077 |
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It has been known that uniformization of a beam with a Gaussian profile is possible utilizing odd-order nonlinear forces*. Here, we investigate uniformization of the transverse beam profile using nonlinear-focusing forces produced by multipole magnets in detail. We show that it is possible to uniformize an asymmetric beam as well as a Gaussian beam utilizing the odd and even-order nonlinear forces in combination**. It enables us to perform high-uniformity irradiation at a constant particle fluence rate over the whole area of a large target. A research and development study of the beam uniformization system composed of sextupole and octupole magnets is now in progress at the JAEA AVF cyclotron facility. Some results of preliminary experiments on beam uniformization are also reported.
*P. F. Meads, Jr., IEEE Trans. Nucl. Sci. 30, 2838 (1983). |
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| THPC046 | Heating Rate of Highly Space-charge-dominated Ion Beams in a Storage Ring | 3080 |
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We investigate the heating process of highly space-charge-dominated ion beams in a storage ring, using the molecular dynamics simulation technique. To evaluate the heating rate over the whole temperature range, we start from an ultra-low-emittance state where the beam is Coulomb crystallized, apply perturbation to it, and follow the emittance evolution. When the ring lattice is properly designed, the heating rate is quite low at ultralow temperature because random Coulomb collisions are suppressed*. It gradually increases after the ordered state is destroyed by perturbation, and comes to a peak when the beam reaches a liquid phase. The dependence of the heating behavior on the beam line density and betatron tune is explored systematically. The effect of lattice imperfection on the stability of crystalline beams is also confirmed.
*J. Wei and A. M. Sessler, EPAC'96, p.1179. |