Polycarbonate/chopped carbon fiber composites with increasing fiber content show reduced mean fiber length and mean fiber aspect ratio, enhanced thermal stability, conductivity, strength and modulus, accompanying an obvious ductile–brittle transition.

No abstract

A tunable magnetically insulated transmission line oscillator (MILO) is put forward and simulated. When the MILO is driven by a 430 kV, 40.6 kA electron beam, high-power microwave is generated with a peak output power of 3.0 GW and frequency of 1.51 GHz, and the relevant power conversion efficiency is 17.2%. The 3-dB tunable frequency range (the relative output power is above half of the peak output power) is 2.25-0.825 GHz when the outer radius of the slow-wave structure (SWS) vanes ranges from 77 mm to 155 mm, and the 3-dB tuning bandwidth is 92%, which is sufficient for the aim of large-scale tuning and high power output.

No abstract

The tunable high power microwave source (HPM’s) is considered to be an important research direction. However, the corresponding mode converter has been researched little. In this paper, a high-efficiency tunable mode converter (HETMC) is investigated for high-power microwave applications. The HETMC that is consisted of coaxial inner and outer conductors, with four metal plates arranged radially, at 90° in the coaxial gap, and matching rods can transform coaxial transverse electromagnetic (TEM) mode to TE11 coaxial waveguide mode. The results show that adjusting the length of the downstream plate, and the distance between the rods installed upstream and the closest edges of the plates, can improve the conversion efficiency and bandwidth remarkably. Moreover, when the frequency ranges from 1.63 GHz to 2.12 GHz, the conversion efficiency is above 95% between 1.63 GHz and 2.12 GHz with a bandwidth of 26.1%. Besides, the unwished reflection and transmission can be eliminated effectively in the HETMC.