• I.N. Onishchenko, V. Kiselev, A. Linnik, V. Mirny, V. Uskov
  NSC/KIPT, Kharkov

Essential increase of wakefield intensity at excitation by a long train of relativistic electron bunches when the rectangular dielectric structure is filled with plasma was experimentally observed. A train of bunches was produced by the linear resonant accelerator. Parameters of the beam: energy 4.5 MeV, pulsed current 0.5 A, pulse duration 2 mksec. Such macro-pulse consists of a periodic sequence of 6000 electron bunches. Each electron bunch has duration 60 psec, diameter 1.0 cm, angular spread 0.05 mrad, charge 0.16 nC. Bunches repetition frequency is 2805 MHz. Transit channel for bunches is filled with gas at various pressure. The first portion of the bunches ionizes gas so that plasma frequency is equal to bunch repetition frequency and to the frequency of principal eigen mode of the dielectric structure. Excitation enhancement at such resonant conditions is being studied taking into account the improvement of bunch train propagation in the transit channel and electrodynamics change of the dielectric structure at filling with plasma.