Commissioning experience and beam physics measurements at the SwissFEL Injector Test Facility

TL;DR

The SwissFEL Injector Test Facility's commissioning and measurements demonstrated key beam parameters, advanced instrumentation, and tested an in-vacuum undulator, supporting the development of the SwissFEL X-ray laser.

Contribution

This paper provides a comprehensive overview of the commissioning experience, beam physics measurements, and technological advances at the SwissFEL Injector Test Facility.

Findings

Demonstrated electron beam parameters suitable for FEL operation

Advanced instrumentation and beam characterization methods developed

Tested in-vacuum undulator prototype generating VUV and optical radiation

Abstract

The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and testbed for the development and realization of SwissFEL, the X-ray Free-Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including a transverse deflecting rf cavity. It delivered electron bunches of up to 200 pC charge and up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of an FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultra-low-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measurements performed during the operation of the test facility, including the results of the test of an in-vacuum undulator prototype generating radiation in the vacuum ultraviolet and optical range.