Search

In order to improve the efficiency and obtain high output power with pure mode, 3-D particle-in-cell simulations are made on a novel coaxial triode vircator. Simulation results show that due to the appearance of the additional cylindrical cathode rod along the centerline, pure TM01 mode can be obtained in the output region. Simulation results also show that high-efficiency and pure TM01 mode output maintains even for output waveguide radius (equals anode radius) somewhat larger than the cutoff radius of the TM02 mode ( Rc,\mathrm {TM02} ). When the cathode and anode gap keeps unchanged, most optimal structure values can be scaled for models with different anode radius. By careful optimizations, the efficiency can reach 15% at an output power of 1.7 and 2.2 GW, respectively, for anode radii equal 5.6 and 6.6 cm ( < Rc,\mathrm {TM02} ); For anode radii equal 7.6 and 8.6 cm ( > Rc,\mathrm {TM02} ), the efficiency is about 13% at an output power of 2.5 and 2.9 GW, respectively. The operating frequencies all are about 3.6 GHz. [ABSTRACT FROM PUBLISHER]

A semitransparent cathode is proposed for an efficient operation of the relativistic magnetron (RM) with axial extraction. The semitransparent cathode is a kind of shaped cathode. It is achieved using a cylindrical cathode with longitudinal strips removed. The cross section of each removed strip is fan-shaped and all the emit strips are connected in the central area of the cathode. Results of the 3-D particle-in-cell simulations show that the using a semitransparent cathode yields similar performance benefits compared with that using the transparent cathode proposed by the University of New Mexico. Simulation results also show that output characteristics of the RM using the semitransparent cathode are insensitive to the depth and width of each cathode slot. Thus, the semitransparent cathode might be more robust for practical applications. [ABSTRACT FROM PUBLISHER]

A novel coaxial relativistic backward-wave oscillator (C-RBWO) for millimeter wave generation is proposed and studied by simulation. In the proposed C-RBWO, a coaxial structure is used in the beam-wave interaction region. According to the dispersion relations in the slow-wave structure region, a new simple and effective reflector is designed for effective cutoff the backward-wave at the electron-injector end. Nonuniform corrugation depth is used to increase the efficiency. For an electron beam with 263-kV voltage and 610-MW power, about 80-MW output power is obtained by simulation at 96.2 GHz. The C-RBWO operates at a low magnetic field (3.7 T) below the cyclotron resonance value (about 10.2 T). The output efficiency is beyond 13%. [ABSTRACT FROM PUBLISHER]

An improved compact and high-efficiency A6 relativistic magnetron (RM) with axial extraction is proposed and studied by numerical simulations. Compared with the conventional design, two pairs of diametrically opposite cavities (four cavities) of the anode block are tapered onto the horn antenna for TE11 mode radiation with high output efficiency. Due to the cutoff radius of the TE11 mode is the smallest in the circular waveguide, the diameter of the output waveguide could be reduced obviously. And the total axial length of the horn antenna could also be shortened accordingly. At the same time, a semitransparent cathode is used for quick startup and efficient beam-wave interaction. Results of the 3-D particle-in-cell (PIC) simulations show that over 1.25 GW output power with TE11 mode is obtained at ${S}$ -band, when the electron beam voltage is 600 kV and the applied axial guiding magnetic field is 0.54 T. And the efficiency exceeds 66%. Simulation results also show that the output efficiency of the proposed RM keeps almost unchanged between 550 and 620 kV with fixed guiding magnetic field. [ABSTRACT FROM AUTHOR]