The use of microwave superradiance pulses for high-gradient acceleration of electrons in a cylindrical waveguide with a dielectric insert

We theoretically study the acceleration of electrons by a 38-GHz subnanosecond superradiance pulse with a 3-GW peak power in a cylindrical waveguide with an annular dielectric insert. It is shown that the energy gain and the accelerating gradient depend on the dielectric constant of the insert, namely, the energy gain decreases and the maximum accelerating gradient increases with increasing the dielectric constant. For an electron with an initial energy of 300 keV, the maximum accelerating gradient reaches 120 MV/m with an energy gain of 7.2 MeV in a waveguide with a polystyrene insert ($\varepsilon$ = 2.53) and 220 MV/m with an energy gain of 4.5 MeV in a waveguide with a quartz insert ($\varepsilon$ = 3.81).