Numerical simulation of an improved type C-band MILO
Using a 2.5 dimensional fully electromagnetic particle-in-cell(PIC) code,a new type of MILO was designed.A circle is placed at the launch point to improve the interaction between the electron beam and the fields supported by the slow wave structure,thus to control the beam current density at the launch point,and to minimize the loss of the electron beam energy.The inner radii of the extractor vanes are slightly larger than those of other SWS vanes,which increases the axial group velocity and enhances the microwave output power and efficiency.Implementation of two RF choke vanes stops the leakage of microwave pulse power toward the diode,and makes the device more compact than the conventional MILO.High power microwave is generated from the device with an average output power of 2 GW,a frequency of 3.51 GHz and an efficiency of 10%.