Experimental observation of Cherenkov superradiance from an intense electron bunch

Experimental results are presented of the observation of stimulated Cherenkov radiation when intense subnanosecond electron bunches were moving through a dielectric-loaded waveguide. The ultrashort duration microwave pulses (up to 400 ps which is equivalent to ∼10 periods of the radiation) in combination with specific dependencies of peak microwave power on interaction length demonstrate that this emission can be interpreted as coherent superradiant (SR) emission. The peak power associated with the SR emission was ∼1–2 MW. The spectrum of radiation belongs to the frequency range 38–48 GHz. The experimental results are compared with theoretical analyses.