Activities are described in a study program to develop parametric data for generation, control, conversion, and transmission of electric power for space vehicles. The coolant temperature considered for the generator is 500 to 1500 deg F, the voltage levels are 5000 to 50,000 d-c, and the ratings are 1 to 10 Mw. Research during the period revealed that the rectifier efficiency of the Si-diode systems is higher than the gas-tube diode system in the desired power range. The Si-diode system is also lighter. In comparison with the Si-rectification system, the gas-tube rectifier system offers higher allowable coolant temperature range in exchange for higher required weight, volume, and coolant flow. (J.R.D.)