c. The power dissipation at the cathode was 235 watts. d. The power dissipation at the anode was 647 watts. e. The sun line is normal to the radiator as shown. Applying these parameters, the cathode radiator was calculated to be a truncated 85 degree cone with a 10 cm (3.9 inches) base while the anode radiator is a truncated 140 degree cone with a 48 cm (18.9 inches) base. The radiator material used was Pyrolytic Graphite. This material was selected because of its high temperature strength and its unique thermal conductivity characteristics. In an effort to reduce the radiated heat flux on the waveguides from the anode radiator, analyses were conducted with a sheet of metallized (both sides) Kapton insulation inserted between them. Results of these analyses are itemized for comparison. The klystron tube design was not as well defined as that of the amplitron throughout the study and its power level and focusing technique were altered as new data were generated. The PPM design at 6 kW output changed to solenoid focused designs at higher powers culminating in the 48 kW design. The material in Figures 6-29 and 6-30 relates to the 6 kW version which was later scaled to the larger power level for the aluminum insulated case. As shown in Figure 6-30, temperatures are much lower for the 48 kW tube due to a lower radiator temperature. The inherent lower efficiency and the configuration of the klystron results in excessive temperature when cooled by a passive approach to heat transfer. Body temperature reached 615°C. In order to provide some comparison with the amplitron, it was assumed that a heat pipe jacket could be designed to surround the klystron and keep the magnets to a maximum temperature of 350°C (Point D). This heat pipe is connected to a radiator as illustrated in Figure 6-29. In order to maintain the heat pipe temperature at no higher than 350°C, this radiator was calculated to be a truncated 140 degree cone with a 64 cm (25.2 inches) base.
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