Effective Numerical Simulations of Multipactor by WBPAT Theory

We propose a fast electromagnetic particle-in-cell (EM-PIC) method to simulate multipactor in waveguide devices. First, complex amplitudes (amplitudes and phases) at multiple frequencies are quantitatively extracted by using the wideband power-to-amplitude transformation (WBPAT) algorithm in the finite-difference time-domain (FDTD) method. Then the charged particles are advanced one way from the time-domain (TD) electromagnetic (EM) fields transformed from the complex amplitudes without considering the space-charge effects. Therefore, the conventional FDTD iterations and interpolations to cell nodes are avoided at the iterative stage. As a result, the simulation efficiency can be greatly improved. The efficiency can be further promoted by using the time step magnification and local region simulation. The proposed method can also be utilized for analyzing the multicarrier multipactor. For the
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-band impedance transformer under the excitations by different multicarrier waveforms, the simulation speed of the proposed method can be improved by several orders of magnitude and the accuracy of the power threshold is comparable with the self-consistent simulation.