Closed cycle MHD power generation system driven by nuclear reactor for space exploration
For deep space explorations, we have to develop high-efficiency, high-reliability and high-performance electric power generation system. In this paper, a closed cycle magnetohydrodynamic (CCMHD) power generation system directly driven by a nuclear fission reactor (NFR) was proposed and investigated. Output electric power level is multi-MWe. Particularly, influence of the number of compressor stages, the regenerator efficiency and the radiator temperature on total plant efficiency and on specific mass (kg/kWe) was analyzed. Proposed system was expected to provide over 55% of total plant efficiency with the radiator temperature of 300 K. The estimated specific mass was about 2/spl sim/3 (kg/kWe) for 2 MWe output and 1/spl sim/2 (kg/kWe) for output power over 3 MWe level.
Estimation of Specific Mass for Multimegawatt NEP Systems Based on Vapor Core Reactors with MHD Power Conversion
Very low specific‐mass power generation in space is possible using Vapor Core Reactors with Magnetohydrodynamic (VCR/MHD) generator. These advanced reactors at the conceptual design level have potential for the generation of tens to hundreds of megawatts of power in space with specific mass of about 1 kg/kWe. Power for nuclear electric propulsion (NEP) is possible with almost direct power conditioning and coupling of the VCR/MHD power output to the VASIMR engine, MPD, and a whole host of electric thrusters. The VCR/MHD based NEP system is designed to power space transportation systems that dramatically reduce the mission time for human exploration of the entire solar system or for aggressive long‐term robotic missions. There are more than 40 years of experience in the evaluation of the scientific and technical feasibility of gas and vapor core reactor concepts. The proposed VCR is based on the concept of a cavity reactor made critical through the use of a reflector such as beryllium or beryllium oxide. Va...
Low-Power Ion Thruster Development Status
Summary As part of an activity to address the need for a light weight, low power, high specific impulse propulsion option for small spacecraft, a sub-0.5 kW, 8 cm beam diameter, prototype ring-cusp ion thruster, and associated test support equipment, were fabricated. A preliminary performance assessment of the thruster on xenon propel- lant was completed over an input power envelope of 0.1- 0.3 kW, and the operation of various components were documented. Discharge chamber performance values for the ring-cusp thruster were 0.68 to 0.78 propellant efficiency, and discharge losses from about 320-380 W/A at 0.1 kW, down to about 220-250 W/A at 0.3 kW thruster input power. Discharge voltages ranged from 25-32 V, with most data at I 29 volts. The documented discharge chamber performance for the thruster met or exceeded the previously-published targets of about 330 W/A at 0.1 kW to 266 W/A at 0.3 kW. The perveance-limited beam current measured for thruster ion optics yields about a 200 volt margin at the target 0.1 kW condition, and about 125 volt margin at 0.3 kW. The perveance-per-unit area for the optics are nearly identical to that previously reported for 30 cm optics of comparable electrode geometry and cold interelectrode gap. Measurements of electron-backstreaming indicate a large