Transmission Characteristics. Ribbon Electron Beam In The Wiggler Magnetic Field Research

From 80th decade of 20th century, higher currents beam source is urgent need for high power millimeter wave devices, ranging from electronic countermeasure to satellite communication and deep space instrumentation and so on, Sheet electron beam is one of the most important one. Sheet electron beam have lots of attractive virtues. For example, when it was used in microwave tubes, it can carry higher currents than those with solid beams. Since sheet beam current would not be limited in perveance, which means current is increased by increasing the width of the beam. On the other hand, Sheet electron beam could greatly decrease the space charge force that might reduce the focusing requirement. Converting from cylindrical solid to sheet beam may permit substantial reduction in space charge effects on the efficiency of devices. The more high frequency we need smaller of the SWS (slow wave structure) section. We can use sheet electron beam in micrometer or microwave device, while ring or cylindrical electron beam can't be used in such device. Finally, sheet electron beam could put close to SWS, which makes the tubes more efficiently than ring or cylindrical electron beam tubes.Although sheet beam has so many merits, the ring and cylindrical electron beam tubes always were the mainstream of scientific research for past 50 years, because sheet electron beam was difficult in focusing. Transmitting in solenoid magnetic fields, sheet electron beam comes into being Diocotron instability, which could lead to collapse in beam propagation. This paper begins with space charge wave theory and get surface wave in half infinite sheet electron beam. Than we assume sheet electron beam was layered and deduce the Diocotron instability.According to ring electron beam tube used PPM focusing, Wiggler field is used to focus sheet electron beam. We not only derive the equivalent single-particle equation of motion, but also deduce the envelop equation for the edge of an elliptical beam, with both space-charge and emittance effects. We develop we develop relations between the required Wiggler peak field strength and beam emittance, and limitations on the period length to maintain orbit stability. 3D (three dimensional) PIC (particle in cell) code MAGIC, was used to simulate electron behave. In case of z = (u|â†')₀t((u|â†')₀ as the velocity of electron is confirmed, "t" means the section of position "z" in 2D simulations), Diocotron mode was simulated with infinitely wide sheet electron beam and sheet beam in wave guide focusing by uniform solenoid magnetic field. We observe the influence of Diocotron mode by each parameter. Then the Wiggler field is used to focus sheet electron beam, and the simulation results indicate that Wiggler field can restrain the Diocotron instability. Besides these, the influence of Wiggler field's magnitude and period on the Diocotron instability is investigated based on the PIC simulation.