Dark Current Studies for SwissFEL

TL;DR

This paper investigates dark current in SwissFEL, combining simulations and experiments to assess activation levels and component behavior, crucial for regulatory approval of this advanced light source.

Contribution

It provides the first detailed simulation and experimental analysis of dark current effects in SwissFEL, informing safety and operational protocols.

Findings

Dark current levels are higher in SwissFEL compared to third-generation sources.

Simulations with ASTRA, Elegant, and OPAL match experimental data.

Results inform safety measures and component design for SwissFEL.

Abstract

Activation of the surroundings of an accelerator must be quantified and those data provided to the official agencies. This is a necessary step in obtaining the authorization to operate such an accelerator. SwissFEL, being a fourth generation light source, will produce more accelerated charges, which are dumped or lost, than conventional third generation light source, such as the Swiss Light Source. We have simulated the propagation of a dark current beam produced in the photoelectron gun using tracking codes like ASTRA and Elegant for the current layout of SwissFEL. Experimental studies have been carried out at the SwissFEL test facilities at PSI (C-Band RF Stand and SwissFEL Injector Test Facility), in order to provide necessary input data for detailed study of components (RF gun and C-band RF structures) using the simulation code OPAL. A summary of these studies are presented.