High-frequency electron beam modulation, transportation and its interaction with slow-wave structure

Abstract

Summary form only given, as follows. We present experimental results of a high-frequency (HF) modulated electron beam generated in a diode with a plasma cathode. The plasma was prepared by an incomplete surface discharge which was ignited by applying a driving pulse to a ferroelectric sample. The sample was made of a BaTiO/sub 3/ disk placed inside a cathode box with an output window covered by a stainless steel grid. The-experiments were carried out with an accelerating voltage in the range of 40-120 kV and pulse duration up to 30 /spl mu/s. Data concerning the influence of the accelerating voltage and the diode geometry on the parameters of the modulated electron beam and its power are presented. We also present data concerning the electron energy and the total current of the beam in the diode as a function of the applied voltage. The maximum amplitude of the modulated beam current reaches 65 A which corresponds to a beam power of 4.5 MW. The transport of the HF electron beam in a guiding external magnetic field as well as the beam interaction with a helical slow-wave structure (SWS) were demonstrated. The beam modulated at 190 MHz with an amplitude up to 25 A was transported in the magnetic field (0.9-1.8 kG) along a distance of 50 cm. In addition, it was shown that the modulated beam could be efficiently transported through the SWS without any external magnetic field. A backward-wave oscillator regime at an operating frequency /spl sim/1 GHz with a non-modulated electron beam emitted by the ferroelectric cathode is demonstrated as well.