Effects of Frequency Spreads on Beam Breakup Instabilities in Linear Accelerators
Abstract
Beam breakup (BBU) instabilities result from the coupling between the transverse motions of the electron beam and the deflecting modes of the accelerating structures. Control of BBU growth relies mainly on the reduction of this coupling. This can be achieved either by restricting the transverse motions of the beam through external focusing (e.g., solenoidal, quadrupole or higher order focusing, ion channel, etc.) or by proper modification of the deflecting modes (e.g., stagger tuning, lowering of the quality factor Q of the deflecting modes, etc.). Structural mode frequency spreads are shown to have a rather different influence on beam breakup growths than betatron frequency spreads. The present analytic and numerical studies show that a finite spread in the breakup mode frequency leads to an algebraic decay of the beam breakup instabilities even if the quality factor Q yields infinity. Effects of stagger tuning are examined. Keywords: Beam structure interaction, Transverse modes suppression.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 11, 1989
- Accession Number
- ADA208318
Entities
People
- Dennis G. Colombant
- Yueying Lau
Organizations
- United States Naval Research Laboratory