Wakefield excitation in dielectric wavguides by a sequence of relativistic electron bunches

The results of theoretical and experimental studies of the wakefield excitation in a dielectric waveguide of a finite length by a long sequence of relativistic electron bunches have been carried out to reveal the possibility of the wakefield amplitude enhancement at summing coherent fields of separate bunches when the bunch repetition frequency coincides with the excited field frequency. It has been theoretically shown that the number of bunches whose wakefields give growth of the total wakefield amplitude is limited and depends on values of waveguide length and group velocity. For the experimental verification of this result the facility has been created, in which, a long sequence of electron bunches, produced by linear resonant accelerator, has been used to excite the wakefield in a dielectric waveguide of various length. In accordance with the theory the stepwise increasing dependence of the wakefield amplitude upon the dielectric waveguide length has been obtained. Stepwise behavior of the dependence evidences the wakefield growth from the each bunch.