Gong Huarong

A method of designing photonic crystal grating slow-wave circuit for Ribbon-Beam microwave travelling wave amplifiers ∗

A method of designing a photonic crystal grating slow-wave circuit in which the cylinders of the 2D photonic crystals dot on a cross-sectional plane is established by calculating the band structures of the 2D photonic crystals, and the eigenfrequency of the equivalent waveguide grating. For calculating the band structures, the eigenvalue equations of the photonic crystals in the system of photonic crystal grating slow-wave circuit are derived in a special polarization mode. Two examples are taken to show the method. The design result is validated by the scattering parameters of the same circuit. The result indicates that there exists no photonic band gap if the metal gratings do not extend into the photonic crystals; the design of the circuit without the metal gratings extending into the photonic crystals is less flexible than that with the metal gratings extending into the photonic crystals.

The Analysis of Ion Noise With Beam-Wave Interaction in Klystron by Two dimension Particle Simulation Method

Ion noise in output signal in klystron was obtained by particle in cell method. The phase fluctuation in output signal is caused by the change of the beam current DC velocity which is affected by the change of the ion amount. The phase of output signal changed with the change of beam electron amount.

A Transient-State Simulation of Ionization Effects in a Microwave Tube

A model for studying the ionization effects in a microwave tube has been developed. This model is simulated by a two-dimensional particle-in-cell code with the Mont Carlo collision model for the electron-neutral ionization process. The transient-state process of ion noise and ion focusing effects are observed. A simple theory about ion motion is given for interpreting the phenomenon of the ion moving to the wall of the tube when the beam is not neutralized. The computed result agrees with the experiment and simulation result.