English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The operation of Ultrafast Electron Diffractometers (UEDs) and Free-ElectronLasers (FELs) relies on high-brightness electron beams produced byradio-frequency (RF) photocathode guns. The next generation of high-repetitionrate UEDs and FELs requires electron beams with a high average brightness. Tothis end, we introduce a continuous wave RF photocathode gun at 325 MHz with anAPEX-like geometry. The gun allows for the production of electron beams withvery high both peak and average 5D brightness while having moderate RF powerconsumption. The gun is operated in blowout regime with an energy gain of 0.4MeV and a peak cathode field of 35 MV/m. Via massive numerical simulations, weexemplify three regimes of the gun operation: (i) 160 fC electron beams with a5-nm-scale emittance for UEDs, (ii) 1.6 pC beams with a 20-nm-scale emittancefor table-top FELs and dielectric-based accelerators, and (iii) 16 pC beamswith a 50-nm-scale emittance for inverse Compton sources and otheraccelerator-based photon sources. We introduce a simple analytical model forthe formation of the virtual cathode - the onset of the suppression ofphotoemission current due to space-charge forces. The model accounts for thelaser pulse duration. Furthermore, our extensive numerical simulations indicatea well-pronounced maximum in the 5D beam brightness for the laser spot radiusapproximately 150% of that corresponding to the onset of the virtual cathode.The finding does not support the common approach in the literature that in theblowout regime the laser spot radius must be much larger than the criticalradius corresponding to the virtual cathode onset.

Nanometre-scale emittance beams from a continuous-wave RF gun