Design of W-band sheet beam Extended Interaction Klystron for millimeter-wave appplications
In this paper, the design of sheet-beam Extended Interaction Klystron (SBEIK) is discussed. The SBEIK is initially designed by implementing the preliminary equations and then modelled using CST-Microwave Studio (MWS) to obtain the dispersion characteristics by the Eigen-mode solver. The coupler design is carried out with stepped impedance transformer approach and is optimised to get a return loss of −54 dB. Particle-in-cell (PIC) simulation is carried out in CST-PIC solver indicated an RF output power of 7 kW and a gain of 28.4 dB.
W-band sheet beam klystron design
At millimeter wavelengths, there is a growing need for a small size and weight, high average power RF source. The sheet beam klystron (SBK) is ideally suited to many of these needs. The SBK is characterized by a large rectangular drift tube, which allows the use of a high current, low voltage beam, resulting in a low beam current density, and hence high efficiency and the possibility of PPM focusing.
Study on Transmission Characteristics of Vertical Rail Vibrations in Ballast Track
A plane half-track model and a periodic track-substructure model are established. The spectral element method and spectral transfer matrix method are developed and applied to investigate the track decay rate (TDR) and transmission rate (TR) of the vertical rail vibrations, which can reflect the transmission characteristics in the longitudinal and downward directions, respectively. Furthermore, the effects of different track parameters on TDR and TR are investigated. The results show that the antiresonance frequency of the rail and the out-of-phase resonance frequency of the rail and sleeper form the boundary frequencies of the high-attenuation zone for longwise vibration transmission, where the vibration absorption of the sleeper is significant. The downward transmissibility of vertical rail vibrations is greatest around the antiresonance frequency of the rail. Vertical rail vibrations are primarily transmitted in the downward direction at low frequencies, while they are mainly transmitted along the rail at high frequencies. Stiffer rail pads can make more vibrations transmitted downwards to the sleeper above the antiresonance frequency of the rail, while the changes of other track parameters have different effects on the transmission characteristics. Additionally, a field measurement is performed for verification, and the simulations are well consistent with measurements.