Thermal Management Techniques for Novel Single-Stage Collector of THz Folded Waveguide TWT

Abstract

Folded waveguide traveling wave tubes (FW-TWTs) exhibit maximum potential in sub-THz to THz regime than its counterparts with respect to power and bandwidth, thereby facilitating its application in high data rate 6G communication systems. However, at high frequency, for synchronous and efficient interaction between electron beam and RF wave, FW-TWTs have to be operated at considerably high beam voltages. Furthermore, it has been reported that the interaction efficiency of FW-TWT is very poor; thus, most of the beam energy remains unspent. The efficiency of such devices may be increased by recovering the unspent beam energy in the collector. A corrugated single-stage collector has been designed with multiple periodic corrugations for an FW-TWT considering the size constraints. This geometry modification has resulted in self-trapping of secondary electrons and increased surface area yielding in >84% collector efficiency (~6% improvement in collector efficiency as compared with conventional collector). Detailed thermal and structural analyses of this collector have been carried out for different electrode materials, namely, copper and graphite. Various thermal management techniques have been employed to improve the thermal dissipation which includes forced air cooling, axial grooves on the outer envelope, and radiator fins. Simulation results reveal that a percentage reduction in the maximum temperature of 32.68%, 22.63%, and 72.59% has been achieved using forced air cooling, axial grooves, and radiator fins respectively. Further simulations also show a percentage decrease of 57.14% and 81.41% in the maximum collector temperature by using forced air cooling in combination with axial grooves and radiator fins, respectively. Based on the thermal and structural results, recommendations for the optimum thermal management technique have also been provided.