A description is given of the ribbon lasertron, a new rf amplifier tube designed for linac collider applications. Three design features that permit extension of the lasertron concept to very high frequencies are discussed: a ribbon beam geometry that mitigates space charge depression and facilitates efficient output coupling; a traveling-wave output coupler that is used to obtain optimum coupling to a wide beam; and a gated field-emitter array used for the cathode. Performance calculations for the prototype design are presented.
