RF breakdown experiments and simulations in “cold” slow wave structures (SWSs) are executed. All the SWSs are designed as traveling wave structures, which operate at the π/2 mode of TM01 waves. The experimental results indicate that the input microwave energy is mainly absorbed, not reflected by the RF breakdown process in traveling wave SWSs. Both larger magnitude of Es-max and more numbers of periods of SWSs aggravate the microwave absorption in the breakdown process and bring about a shorter transmission pulse width. We think that the critical surface E-field of the multi-period SWSs is 1 MV/cm. However, little correlation between RF breakdown effects and Bext is observed in the experiments. The simulation conditions are coincident with the experimental setup. Explosive emissions of electrons in the rounded corner of SWSs together with the ionization of the gas layer close to it supply the breakdown plasma. The gas layer consists of water vapor and hydrogen gas and has a pressure of 1 Pa. Different kinds of circumstances of SWSs are simulated. We mainly concern about the characteristic of the plasma and its influence on microwave power. Comprehensive simulation results are obtained. The simulation results match the experimental results basically and are helpful in explaining the RF breakdown phenomenon physically.

No abstract