Exploratory study of PWFA-driven FEL at CLARA

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This project "Exploratory Study of PWFA-FEL at CLARA" will develop electron-beam driven plasma wakefield accelerator (PWFA) based free-electron-lasers (FEL). FEL's are advanced coherent light sources which allow imaging of ultrasmall structures and ultrafast processes. These 'engines of discovery', today driven exclusively by linac-generated electron beams, are a major part of the STFC strategy https://stfc.ukri.org/files/fel-report-2016/ . Plasma-based accelerators, either driven by laser pulses in laser wakefield accelerators (LWFA) or driven by electron pulses in plasma wakefield accelerators (PWFA), are alternative acceleration methods known to produce short and intense, high energy electron beams. They are therefore increasingly considered as drivers for FEL's in future compact systems. However, a well-known substantial challenge of plasma accelerators is the production of electron beams with sufficiently low emittance and energy spread in order to achieve lasing in an undulator setup. Recent conceptual breakthroughs by the Strathclyde/UCLA-led "E210: Trojan Horse PWFA" collaboration and first experimental evidence obtained at SLAC FACET suggests that PWFA can produce electron beams with emittance and energy spread as well as brightness many orders of magnitude better than state-of-the-art. This would not only allow plasma accelerator electron output to meet the strict requirements to achieve lasing in an FEL, but also to exceed the state-of-the art of the best linac-based machines such as LCLS or European XFEL by many orders of magnitude as regards emittance as well as 5D and 6D brightness. Such beams could have transformative impact, as they may allow the realization of compact and cost-effective FEL's with a performance exceeding those of existing hard x-ray FEL's such as LCLS or the EU XFEL, including novel capabilities such as coherent attosecond-scale, high brilliance, single-spike hard X-rays pulses. We aim to develop this technology as a next-generation photon source for the time after current and upcoming linac-driven FEL's.