摘要：The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling- wave tube is constructed. The electromagnetic characteristics and the beam wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.

摘要：In this paper, we present a design where a bunched relativistic electron beam traversing inside the rectangular dielectric-loaded （DL） waveguide is used as a high power microwave generation device. Two kinds of methods of calculating the electromagnetic （EM） field excited by a bunched beam are introduced, and in the second method the calculation of EM pulse length is discussed in detail. The desired operating mode is the LSM11 due to its strong interaction with the electron beam. For the designed 7.8 GHz operating frequency, with a 100 nC/bunch drive train of electron bunches separated by 0.769 ns, we find that high gradient （〉 30 MV/m） and high power （〉 160 MW） can be generated. An output coupler is also designed which is able to extract the generated power to standard waveguides with a 94% coupling efficiency.

摘要：A directional coupler in a miter bend was designed to monitor the microwave power of the transmission line in an electron cyclotron resonance heating（ECRH） system. It is based on aperture-coupling theory and simulation of an electromagnetic（EM） field to design and optimize the 140 GHz high-power directional coupler. In addition, we simulated the double-aperture directional coupler by using three-dimensional（3D） EM simulation software, in which the central frequency is 140 GHz, coupling factor is about –70 dB, and directivity is greater than 17 dB. The results show that such a coupler is a viable tool for power measurement in high-power transmission systems.

摘要：The output section of a helix travelling wave tube usually contains a helix pitch taper for high rf electron efficiency. By keeping the rf field as synchronous as possible with the decelerating electron beam bunches, the rf field can extract much more energy from the beam, and thus the maximum electron efficiency can be realized. Recently, a global simulated annealing algorithm has been employed to design the helix pitch profile so as to improve the electron efficiency as much as possible. From the numerical results, it is concluded that the electron efficiency can be enhanced by about 4%-8%.

摘要：A method of designing an E-plane power combiner composed of two quarter-arc bent rectangular waveguides is proposed for sub-THz and THz waves. The quarter-arc bent-waveguide power combiner has a simple geometry which is easy to design and fabricate. By HFSS codes, the physical mechanism and performance of the power combiner are analyzed, and the relationship between the output characteristics and the structure/operating parameters is given. Simulation results show that our power combiner is suitable for the combining of two equalpower and reversed-phase signals, the bandwidth of the combiner is wide and can be adjusted by the radius of the quarter-arc, and the isolation performance of the combiner can be improved by adding thin film resistive septa at the junction of two quarter-arc bent waveguides. Meanwhile, an approximate method based on the analytic geometrical analysis is given to design this power combiner for different frequency bands.

摘要：The gyrotron is one of the most promising high-power millimeter-wave sources for electron cyclotron resonance heating（ECRH） in controlled thermal nuclear fusion *** this paper,the design of a high-frequency interaction cavity of a 1 MW/140 GHz gyrotron is described in *** cavity is designed by using eigen mode analysis and radio frequency（RF） behavior *** transitions at the input and output tapers are designed for reducing mode *** the obtained cavity structure,non-linear self-consistent equations are adopted to calculate its output power and efficiency.A particle-in-cell（PIC） method is used to simulate the beam-wave interaction process for obtaining the resonant frequency and output power of the *** PIC simulation results match considerably well with the results obtained by the non-linear self-consistent *** cavity is currently under construction and will be integrated with other components for overall testing.

摘要：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 photonie 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 photonie crystals is less flexible than that with the metal gratings extending into the photonic crystals.

摘要：The 60-GHz traveling-wave tube （TWT） prevails nowadays as the amplifier for the satellite communication and electronic countermeasures. The folded waveguide （FW） is a promising all-metal slow-wave structure （SWS） for the 60-GHz TWT with advantages of robust performance, fine heat dissipation, considerable power and bandwidth. A novel FW periodically loaded with rectangular grooves is analyzed for the purpose of gaining higher power and gain. The rf characteristics are investigated by numerical simulation, and the nonlinear large- signal performance of such a TWT is analyzed by a 3I） particle-in-cell code MAGIC. Compared with normal circuits, relatively higher continuous-wave power （40-56 W） and similar bandwidth （5 GHz） are predicted by simulation. Meanwhile, the designed operation voltage is 10.5 kV, which keeps the low-voltage advantage of the popular helix TWT competitor. The novel FW will favor the design of a broadband and high-power 60-GHz TWT

摘要：A new aspheric surface pre-collimation lenses system for the optical antenna of three-dimensional （3D） imaging of lidar has been optimally designed and simulated by optical design software *** kinds of aspheric surfaces spherical lenses including the sections of spherical,elliptical,hyperbola,and parabola have been *** optical system,including the elliptical cylinder lenses collimation and the optical antenna,can be realized less than 5 rad collimation angle for dot source semiconductor laser beam.

摘要：Both of planar and mesoporous architectures prevail for perovskite solar cells(PSCs).However,it is still an open question how the architecture affects the performance of *** inconsistent results in the references often create *** particular,the specific roles of mesoporous frameworks are yet to be well elaborated and require further *** this study,we carefully compared the properties of perovskite films and the device performances for both architectures to unravel the roles of mesoporous TiO2 framworks in CH3NH3PbI3 *** detailed characterizations of structural,microscopic,optical and electrical properties revealed that the presence of mesoporous TiO2 framework contributed to enlarged perovskite crystal sizes,enhanced light harvesting,efficient electron extration and suppressed charge *** a result,compared with the planar device,the mesoporous device yielded an improved power conversion efficiency of 18.18%,coupled with a reduced *** study reveals the benefits of mesoporous TiO2 framework in PSCs and provides the guidance for the design and optimization of architectures for high-performance devices.