An electron gun producing a spiral electron beam for gyrotron devices comprises means for producing an axial magnetic field propagating the beam axially beyond the anode of the electron gun, and separate electromagnets for producing a transverse "kicker" electromagnetic field beyond the anode and perpendicular to the magnetic propagation field such as to apply a transverse impulse of short duration, imparting a transverse motion, to the electrons to cause them to spiral as they are propagated axially beyond the anode.
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