Abstract
Electron bunch compressors formed of achromat arcs have a natural advantage over the more commonly used chicane compressors in that linearisation of the longitudinal phase space is of the correct sign to compensate for the curvature imprinted by rf acceleration. Here we extend the utility of arc compressors to enable variation of the longitudinal compaction within a fixed footprint. We also show that this variability can be achieved independently order-by-order in momentum deviation. The technique we employ consists of additional dipoles, leading to the advantageous property that variability can be achieved without incurring significant penalty in terms of chromatic degradation. We show this by comparison to an alternative system where additional quadrupoles are utilised to enable variation of momentum compaction. Each of these alternative approaches are being considered in the context of an upgrade of the MAX IV linac, Sweden, to enable a soft X-ray free-electron laser (FEL) in addition to its existing functions.
Highlights
Magnetic bunch compressors are an increasingly common subsystem within linear electron accelerators for high brightness applications. They are used to manipulate the longitudinal phase space of a bunch for which there is a correlation between momentum deviation and longitudinal position caused by a preceding off-crest radiofrequency acceleration
A standard solution adopted by many electron accelerators driving freeelectron laser (FEL) is the variable four-dipole chicane bunch compressor [15]
We have presented two solutions to retrofit variable orderby-order momentum compaction into the MAX IV arclike bunch compressors
Summary
Magnetic bunch compressors are an increasingly common subsystem within linear electron accelerators for high brightness applications. A consideration of the second-order longitudinal dispersion immediately reveals a disadvantage of the more common chicanelike implementations [2,3]; both arclike and chicanelike systems have naturally negative T566 The motivation is to introduce flexibility into the MAX IV facility, our observations on these arclike compressors are generic and have wide potential future applicability in situations where large energy spread beams must be longitudinally manipulated. The schemes hereby proposed are suited to adoption in the rapidly developing field of electron diffraction facilities [11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
