Linear accelerator as an EUV soruce for semi-conductor lithography

I came across this in IEEE Spectrum
https://spectrum.ieee.org/euv-fel
Phil Hobbs got the ASML tin-droplet EUV light source to work, but there now seems to be the prospect of better way to do it, with undulators acting on high energy electron beam as the EUV source.
It has always been a fairly obvious idea, but - as the Spectrum article makes clear - it's not easy to get enough EUV light out.
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Bill Sloman, Sydney