Space tube with high efficiency cooling design approach

Abstract

Heat pipes, utilized in a high power space type traveling-wave tube, provide an efficient means of dispersing heat from areas of high concentration. Heat, generated in the region of the collector and output Circuit, is dispersed throughout the entire tube baseplate area by both longitudinal and transverse heat pipes contained in the baseplate. The results are lowered individual component temperatures and reduced thermal densities throughout the baseplate. The objective of this effort was to extend the power level of helix space tubes by combining a high efficiency cooling design approach with high efficiency electrical design techniques previously demonstrated on lower power space devices. These techniques include velocity tapering of the helix circuit, multi-stage depressed electron collection, low dielectric and conductive shield loading, and integral barrel focusing. A novel technique for transferring barrel heat to the baseplate is introduced. The tube delivers 300 watts of continuous wave RF output power at lower E-band frequencies. Saturated gain levels of 40 dB are obtained at an overall efficiency of 52%. The tube has been designed for conservative cathode loading and exhibits low operating temperature.