5 upgradable to 25 keV free electron laser facility

Abstract

A free electron laser (FEL) facility utilizing a recirculated superconducting radio frequency (SRF) electron linear accelerator (linac) provides the opportunity to achieve about 5 times greater photon energy than an unrecirculated linac facility of similar cost. An electron linac configuration utilizing a 4 GeV unrecirculated, SRF linac could be used to drive a FEL producing 5 keV photons. However, for a similar cost, a recirculated SRF linac system can deliver the 4 GeV electrons for photon energies of 5 keV and provide an upgrade path to photon energies of 25 keV. Further support amounting to about a third of the initial investment would provide additional recirculated SRF linac and cryogenic capacity sufficient to deliver electron energies appropriate for 25 keV photons matching the European XFEL.