Cross-Plane Resonance: A Mechanism for Very Large Amplitude Halo Formation.

Qiang, J. ; Hofmann, I. ; Ryne, R. D.

Technical Information Center Oak Ridge Tennessee

关键词: Resonance;    Amplitudes;    Halo formations;    Transverse;    Emittance;   

RP-ID  :  DE2001783341

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

In this paper we report on the possibility of very large amplitude halo formation due to a cross-plane resonance, based on a core/test-particle model. Previous analyses of halo formation in mismatched beams (which did not involve a coupling of the phase planes) have found that particles may be driven to amplitudes which are limited to typically three times the edge radius by a 2:1 parametric resonance. In the present paper, we systematically study the transverse halo as functions of the longitudinal-to-transverse focusing strength ratio and the longitudinal-to-transverse emittance ratio. We find that, in cases where the longitudinal focusing exceeds the transverse amplitude can be, in principle, unlimited. In this regime (in contrast to the usual in-plane resonance), the halo amplitude increases with a reduction of the space charge. This may have potential relevance to the future superconducting linac design where the longitudinal to transverse focusing ratio could be greater than one.