Emittance growth and halo formation in charge-dominated beams

Bondarev, B.I.; Durkin, A.P.; Murin, B.P.; Jameson, Robert

doi:10.1063/1.49172

Cited by 4 publications

(3 citation statements)

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“…The own field of halo particles is supposed as negligible small. The analytical calculations [2] show that energy of external particle increases when it crosses the compressing uniform beam core and vice versa: particle energy decreases when core extends. R.L.Gluckstern [7] studied the halo particle dynamics in periodically alternating field of mismatched beam core.…”

Section: Halo Formationmentioning

confidence: 99%

“…The heating of halo particles due to compressing core (look [2]) may cause the halo extension in the time of adiabatic growth of the focusing field. We have made corresponding calculations.…”

Section: Adiabatic Transformationsmentioning

confidence: 99%

“…Computational methods were widely used because analytical approaches are effective only in limited idealized cases (for example, K-V distribution). SCD beam study in linear transport and accelerator channels as well as computer code generation were performed and published by authors starting from 1986 [1][2][3][4][5]. The general results were obtained such as: (a) formation of quasi-uniform core and rarefied halo; (b) core oscillation damping with concurrent emittance growth; (c) beam matching using information of input beam distribution in phase space; (d) minimization of the space charge potential energy and concurrent emittance growth; (e) impossibility of halo stripping by diaphragm and so on.…”

Section: Introductionmentioning

confidence: 99%

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The main regularities of core-halo formation in space charge-dominated ion beam

Bondarev

Durking²,

Korenev³

et al.

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

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The laws that govern the charge redistribution in space charge dominated (SCD) beam during its transport is considered. Physical mechanisms of halo production and establishment of steady distribution inside core for matched beams are described. The image-based computer codes were generated and charge density redistribution process in the beam with concurrent phenomena was described. The main regularities of SCD-beam transporting were carried out. High-density core and lowdensity halo with particle active interchange are established in every case. Most of core particles are "exhalo" or "coming-halo" ones which income from halo in previous instant of time or will emerge from core in next instant of time. Final steady states are ones with Coulomb field minimal potential energy. The transition from the SCD-beam initial state into a final steady state is accompanied by particle kinetic energy increasing and emittance growth. A steady state with constant transverse sizes of core can be established. Such beam state would be nominated as matched one. 1.INTRODUCTIONGrowing needs in high-current CW ion linac aggravate both problems of beam losses and radiation purity. It turned out that acceptable beam loss standard is very tight. Linac designers were obliged to study beam physics mechanisms that lead to emittance growth and core-halo formation. Computational methods were widely used because analytical approaches are effective only in limited idealized cases (for example, K-V distribution). SCD beam study in linear transport and accelerator channels as well as computer code generation were performed and published by authors starting from 1986 [1-5]. The general results were obtained such as: (a) formation of quasi-uniform core and rarefied halo; (b) core oscillation damping with concurrent emittance growth; (c) beam matching using information of input beam distribution in phase space; (d) minimization of the space charge potential energy and concurrent emittance growth; (e) impossibility of halo stripping by diaphragm and so on. These results are agreed very closely with ones published by different researchers later. In recent years works on convenient in operation computer codes for space SCD beam physics study were developed using modern image-based computer technology. The new code tools make calculations with ____________________ * Work supported by International Science & Technology Center # E-mail: lidos@aha.ru higher then formerly accuracy. They are adopted for education and training. In recent report a lot of numerical experiments are discussed in order to clear out the main regularities of core-halo formation in SCD ion beam. The results were obtained in the frame of longitudinal and transverse uniform focusing. Solenoids were used directly as focusing elements. This relatively simple focusing gives a possibility to clear demonstration of all essential SCD-beam effects.

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Section: Halo Formationmentioning

confidence: 99%

Section: Adiabatic Transformationsmentioning

confidence: 99%