Slit injection device

Claim 1

In an electron beam-excited laser system comprising an elongated laser cavity containing a gaseous lasing medium and having a foil window therein through which a beam from an electron beam source passes transversely to excite the lasing medium; the improvement comprising: a beam injection device positioned intermediate said laser cavity and said electron beam source for passing a suitably shaped electron beam through said foil window into said cavity and for varying the current density of the injected electron beam, said injection device being composed of a member positioned closely adjacent the foil window and functioning as a support structure for said foil window, said member being provided with a single elongated slit therethrough substantially parallel to a longitudinal axis of the laser cavity, and a plurality of movably mounted plate means positioned adjacent said member on a side thereof opposite from the foil window and defining an elongated aperture substantially parallel to said elongated slit in said member, and means for moving said plurality of plate means for varying said elongated aperture.