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.
Mission Steering Profiles of Outer Planetary Orbiters Using Radioisotope Electric Propulsion
Radioisotope Electric Propulsion (REP) has the potential to enable small spacecraft to orbit outer planetary targets with trip times comparable to flyby missions. The ability to transition from a flyby to an orbiter mission lies in the availability of continuous low power electric propulsion along the entire trajectory. The electric propulsion system’s role is to add and remove energy from the spacecraft’s trajectory to bring it in and out of a heliocentric hyperbolic escape trajectory for the outermost target bodies. Energy is added and the trajectory is reshaped to rendezvous with the closer‐in target bodies. Sample REP trajectories will be presented for missions ranging for distances from Jupiter orbit to the Pluto‐Kuiper Belt.
Right coronary artery stenosis associated with tricuspid valve ring annuloplasty
A 70-year-old man with severe symptomatic functional mitral valve regurgitation underwent successful mitral valve repair combined with tricuspid valve ring annuloplasty. Pre-operative coronary angiography (CAG) showed no significant stenosis. One-and-a-half years later, the patient presented with an acute exacerbation of heart failure. Repeat CAG demonstrated tight stenosis in the right coronary artery (RCA) with arterial kinking that corresponded to the same point as the stenosis where the RCA is the closest to the tricuspid valve ring. The new lesion probably occurred as a consequence of the tricuspid valve ring annuloplasty.