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.
Pin‐Type Gas Cooled Reactor for Nuclear Electric Propulsion
This paper describes a point design for a pin‐type Gas‐Cooled Reactor concept that uses a fuel pin design similar to the SP100 fuel pin. The Gas‐Cooled Reactor is designed to operate at 100 kWe for 7 years plus have a reduced power mode of 20% power for a duration of 5 years. The power system uses a gas‐cooled, UN‐fueled, pin‐type reactor to heat He/Xe gas that flows directly into a recuperated Brayton system to produce electricity. Heat is rejected to space via a thermal radiator that unfolds in space. The reactor contains approximately 154 kg of 93.15 % enriched UN in 313 fuel pins. The fuel is clad with rhenium‐lined Nb‐1Zr. The pressures vessel and ducting are cooled by the 900 K He/Xe gas inlet flow or by thermal radiation. This permits all pressure boundaries to be made of superalloy metals rather than refractory metals, which greatly reduces the cost and development schedule required by the project. The reactor contains sufficient rhenium (a neutron poison) to make the reactor subcritical under wat...
Enhanced Discharge Performance in a Ring Cusp Plasma Source
There is a need for a lightweight, low power ion thruster for space science missions. Such an ion thruster is under development at NASA Glenn Research Center. In an effort to better understand the discharge performance of this thruster, a thruster discharge chamber with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Characteristics of this ring cusp ion discharge were measured without ion beam extraction. Discharge current was measured at collection electrodes located at the magnetic cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of power, which was varied between 20 and 50 W. It was found that ion production costs decreased by as much as 20 percent when the two most downstream cusp electrodes were allowed to float. Floating the electrodes did not give rise to a significant increase in discharge power .even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment.