There is, therefore, an existing interest in noise in magnetrons and a high level of capability in associated computer simulation that could be used to the advantage of the SSP program if it were to support an investigation specifically related to explaining the different operating modes of the magnetron to produce noise or to operate quietly. Such an investigation could be expected to indicate how very low noise and very high efficiency could simultaneously be achieved in the magnetron. Such an investigation could make use of an adaptation to the microwave oven magnetron of currently available software for analyzing crossed-field amplifiers and a parallel activity in providing experimental noise data on the microwave oven magnetron. n. A DISCUSSION OF REQUIREMENTS IMPOSED UPON THE MICROWAVE GENERATOR AND THE ABILITY OF THE MAGNETRON TO MEET THOSE REQUIREMENTS Introduction Of all the technical requirements imposed upon the SPS system, the severest ones may be the requirements imposed upon one of the components of the microwave power transmission subsystem. This component is the generator in the space transmitter. The requirements that such a generator must meet, simultaneously, have been previously listed but are restated as follows: 1. Very high efficiency at all power output levels to reduce the amount of heat that must be radiated to space. 2. Operation at high temperature to take advantage of the relationship that the quantity of heat radiated is proportional to the 4th power of the absolute temperature. 3. Symmetrical geometry that permits the efficient attachment of a heat radiator. 4. Function as a high gain amplifier with the phase of the output power always in phase with the input drive. 5. Very low level broadband noise. 6. Very low level harmonic radiation. 7. Very long life measured in decades. 8. Ability to interface directly with solar array without any intervening power conditioning. 9. Low emission of X-rays. 10. Ability to withstand bombardment by high energetic particles in space. 11. Low ratio of mass to microwave power output. 12. Low cost. 13. Operation at high voltage to reduce losses in power busses. To the paper’s author, with his extensive background in the design of tubes for high power, such a list of simultaneous requirements was challenging, if not indeed intimidating. He was especially surprised at the
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