Design of the radio frequency section of a multiple beam klystron working in the J-band frequency range
The multiple beam klystrons (MBK) offer some distinct advantages over their single beam versions including higher average power, relatively lower operating voltages, higher bandwidth and low individual beam current. In this paper the design of the radio frequency (RF) section of a multiple beam klystron working in the J band frequency range is presented. The RF design and simulation has been carried out using a commercially available three dimensional electromagnetic design code. A cold test model of the RF cavity has been fabricated and its resonant frequency has been characterized. Design of the individual cavities, simulation results of the beam wave interaction as well as the frequency characterization of the fabricated cavity is presented in this paper.
Design of Radio Frequency Cavities for a J-BAND Multibeam Klystron
Abstract This article presents the computer-aided design of the intermediate and input/output cavities of a multi-beam klystron (MBK) working in the J-band frequency range. A coaxial type cavity has been proposed to meet the specified design parameters. The state of the art electromagnetic simulation tool Computer Simulation Technology microwave studio has been used for the design and optimization of the cavity. Different cavity parameters such as the quality factor, shunt impedance, etc. have been estimated with the help of the simulation tool. For the input/output cavities, the issue of symmetric coupling has been studied and a rectangular-shaped central conductor has been proposed to achieve the desired coupling.
Production of xylanase by Aspergillus awamori on complex medium in stirred tank and airlift tower loop reactors
Abstract Aspergillus awamori was cultivated on complex medium containing wheat bran as sole carbon source in the precultures as well as in the main cultures in stirred tank and airlift tower loop reactors. The decomposition of the wheat bran particles by α -amylase and xylanase produced by the fungus was investigated by monitoring the enzyme activities, the CO 2 production rate, the concentrations of reducing sugars, glucose, xylose, phosphate and ammonium as well as by applying transmission electron microscopy. By applying synthetic medium in the preculture, the time lag was longer, the growth faster, the xylanase activity higher in the main culture, than by using wheat bran in the preculture. With increasing the stirrer speed the intimate contact between the pellets and the wheat bran was reduced, which caused a decrease of the growth and the xylanase production. By applying ground wheat bran, filamentous mycelium was formed, the growth and the substrate uptake rates increased, but the xylanase production decreased due to the less intimate contact between the fungus and the wheat bran. In the airlift tower loop reactor filamentous mycelium was formed due to the low specific power input. In spite of the high medium viscosity, high xylanase productivity was obtained. With ground wheat bran the particles were completely covered by filamentous mycelium, medium viscosity strongly increased and as consequence the growth and xylanase production decreased.