2017) A tapered multi-gap multi-aperture pseudospark-sourced electron gun based X-band slow wave oscillator. Applied Physics Letters, 111 (21). ISSN 0003-6951 , http://dx. Abstract The experimental study of a tapered, multi-gap, multi-aperture pseudospark-sourced electron gun based Xband plasma assisted slow wave oscillator is presented. The designed electron gun is based on the pseudospark discharge concept and has been used to generate a high current density and high energy electron beam,

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... ltaneously. The distribution of apertures has been arranged such that the field penetration potency inside the backspace of the hollow-cathode is different while passing through the tapered gap region. This leads to non-concurrent ignition of the discharge through all the channels that is, in general, quite challenging in the case of multi-aperture plasma cathode electron gun geometries. Multiple and successive hollow cathode phases are reported from this electron gun geometry, which have been confirmed using simulations. This geometry also has led to the achievement of ~71 % fill factor inside the slow wave oscillator for an electron beam of energy 20 keV and beam current density 115-190 A/cm 2 at a working argon gas pressure of 18 Pa. The oscillator has generated broadband microwave output in the frequency range 10-11.7 GHz with a peak power of ~10 kW for ~50 ns.