M.A. Gusarova, S.V. Kutsaev, L.V. Kravchuk1, M.V. Lalayan, N.P. Sobenin, S.G. Tarasov

The design of RF devices to be used in charged particle accelerators must provide these devices be entirely multipactor discharge-free. Discharge occurrence in vacuum area could appreciably spoil the device operation. Multipactor dissipates RF power, leads to prolonged conditioning, causes excessive heating and even leads to breakdown in most severe cases. This phenomenon is the most dangerous for superconducting devices because of possible quench and fall out of superconducting state to normal one. In order to provide the device being multipactor-free at design stage the simulation code was developed and tested. This code could be used for multipactor discharge simulation in number of RF devices for example used in charged particle accelerators. Code accepts different structures (axially symmetric and non-symmetric ones), made of several materials and operated either in standing or traveling wave modes. The simulation is based on electron non-relativistic motion in time harmonic electromagnetic field equation solving. Device to be simulated is defined by its geometry and materials properties namely the electron energy range providing secondary electron emission yield exceeding one. The multipactor is possible in case the stable electron trajectories are found. The simulation results indicate the device dangerous areas where multipactor could occur and cor-responding electromagnetic field strength levels. Code was thoroughly tested on both simple structures allowing analytical solution for field strength levels causing multipactor and set of devices whose operation was experimentally studied. Simulation code results are in good coincidence with data obtained by other methods. Analytical solution and numeric simulation made for narrow rectangular waveguide operated at 1,3 GHz and 3 GHz results deviate in less than 1%.