학술논문
SwissFEL double bunch operation
Document Type
article
Author
Martin Paraliev; Arturo Alarcon; Vladimir Arsov; Simona Bettoni; Roger Biffiger; Marco Boll; Hans Braun; Alessandro Citterio; Paolo Craievich; Andreas Josef Dax; Philipp Dijkstal; Sladana Dordevic; Eugenio Ferrari; Franziska Frei; Romain Ganter; Zheqiao Geng; Christopher Gough; Nicole Hiller; Martin Huppert; Rasmus Ischebeck; Pavle Juranic; Mario Jurcevic; Babak Kalantari; Roger Kalt; Boris Keil; Christoph Kittel; Waldemar Koprek; Daniel Llorente; Florian Löhl; Alexander Malyzhenkov; Fabio Marcellini; Goran Marinkovic; Gian Luca Orlandi; Cigdem Ozkan Loch; Marco Pedrozzi; Eduard Prat; Sven Reiche; Colette Rosenberg; Thomas Schietinger; Serguei Sidorov; Alexandre Trisorio; Carlo Vicario; Didier Voulot; Guanglei Wang; Riccardo Zennaro
Source
Physical Review Accelerators and Beams, Vol 25, Iss 12, p 120701 (2022)
Subject
Language
English
ISSN
2469-9888
Abstract
SwissFEL has a unique capability, among the normal conducting linac-based light sources, to simultaneously serve two separate undulator lines (Aramis and Athos) up to the machine repetition rate of 100 Hz using the double bunch operation mode. It increases twice the experiments throughput of the facility with modest additional investment. Two electron bunches spaced 28 ns apart are extracted from the cathode by two laser pulses with individually controlled repetition rates. The bunches are accelerated up to about 3 GeV in the main linac using the same rf macropulse. After separation, one bunch serves the Athos soft x-ray beamline and the other is further accelerated to serve the hard x-ray beamline – Aramis. A fast and high-stability beam kicker separates the two bunches without disturbing the electron beam and consequently the x-ray lasing. The timing and control system sets hybrid machine modes utilizing independent operation of the two undulator lines with individually programmed repetition rates. Beam diagnostics and feedback systems have to operate with two closely spaced bunches where the two beams share the same machine path. The low-level rf system manipulates the rf amplitude and phase within a fraction of the rf macropulse to provide decoupling of the acceleration parameters of the first and the second bunch. This manuscript presents measurements that show that the bunch separation does not degrade FEL lasing stability.