ELECTROMAGNETIC-WAVE-PUMPED FREE-ELECTRON LASER IN A PLASMA CHANNEL

An intense short laser pulse or a millimetre wave propagating through a plasma channel may act as a wiggler for the generation of shorter wa velengths. When a relativistic electron beam is launched into the chan nel from the opposite direction, the laser radiation is Compton/Raman backscattered to produce coherent radiation at shorter wavelengths. Th e scheme, however, requires a superior beam quality with energy spread less than 1% in the Raman regime.