High power pulsed microwave source

Claim 1

Apparatus for generating microwave energy pulses in the megawatt power range comprising, in combination, a hollow anode electrode of frustro-conical shape; a cathode electrode of conical shape, said cathode being centrally positioned within the interior of said hollow anode so that an annular channel area exists between the outer surface of said cathode and the inner surface of said anode; means for generating a pulsed magnetic field within said channel area whose direction is parallel to the slant surface of said cathode; means for applying to one of said electrodes a short duration voltage pulse when said pulsed magnetic field has maximum intensity, the rise time, length and magnitude of said voltage pulse being such that electrons emanate from said cathode by a cold field emission process and form a pulsed annular beam of relativistic electrons carrying currents of kA magnitude; a cylindrical conducting member having its outer surface notched over its length; and a hollow, cylindrical conductor surrounding said cylindrical member and spaced therefrom such that said notched surface and the inner wall surface of said conductor form a ridged circular wave guide section, said cylindrical member and said cylindrical conductor being positioned such that said pulsed annular electron beam enters one end of said ridged circular wave guide section and thereafter travels down the length thereof, said electron beam and the backward wave produced therefrom which is propagating in an opposite direction to said beam interacting to generate a megawatt microwave energy pulse which is radiated from the other end of said ridged wave guide section.