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Poster session: Beam dynamics in accelerators and storage rings, cooling methods, new methods of acceleration

P.87. D.Kayran, V.N.Litvinenko (Brookhaven National Laboratory, USA)

Result of a merger system optimization in present of strong space charge force for high current BNL's R&D ERL

The R&D Energy recovery linac (ERL) is under construction in Brookhaven National Laboratory. This ERL will be used as a test-facility for many R&D projects relative with high current high brightness ERL's issues. One of the goals of this ERL is demonstrate electron beam with high charge (5 nC) per bunch and extremely low normalized emittance at maximum energy 20 MeV. In contrast with operational high brightness electron accel- erators, axisymmetric systems operating normalized beam emittances at one mm-mrad level, all presently operating Energy Recovery Linacs (ERLs) produce in order of magni- tude larger emittances in 10-to-20 mm mrad range. One of the reasons of emittance growth in merger system is the use of dipole magnets, which mix transverse and longitu- dinal degrees of freedom, and, consequently, can provide for conditions violating emit- tance compensation conditions. In this paper we discuss the reasons of emittance growth in merger system of the operational ERLs. We compare performances of the BNL's ERL system with the most popular ERL merger system designs.

Dr. Dmitry Kayran: dkayran@bnl.gov

P.88. A.A.Asseev, P.T.Pashkov, S.V.Sokolov (Institute for High Energy Physics, Protvino, Russia)

New State of the Accelerated Beam at its Interaction With a Thin Inter- nal Target During Extraction of Particles From the Accelerator.

In the process of investigations at the IHEP proton synchrotron (Protvino, Russia) of the new thin targets which cardinally improved the time structure of the beams extracted si- multaneously for 5-6 experiments a new state of the circulating beam was discovered: the bunched beam of protons having the clear expressed single-turn structure after the fast ejection of 25 bunches changes its state due to interaction with the thin target and turned out in two phases - the bunched and debunched one simultaneously. The second phase of the circulating beam provides an improvement of the time structure of the extracted beams of the secondary particles and primary protons by about an order of magnitude. Influence of the thin target is universal: an appearance of the second phase of the accelerated beam on the flat top of the magnetic cycle does not depend on intensity (number of the acceler- ated bunches). It takes place even at injection from the booster and acceleration only a few (3-5 instead of 30) bunches.

Dr. Alexey Akimovich Asseev: Alexey.Asseev@ihep.ru


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