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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Pressure ramp programmer; IMBLMS Phase B4 Additional Tasks: Task 3.0 pressure ramp programmer

A pressure ramp programmer model was designed, fabricated and tested. This model, in conjunction with an automatic blood pressure monitor, automatically controls the pressure in the blood pressure monitor arterial cuff. The cuff pressurization cycle is designed to maximize accuracy and repeatability of blood pressure measurements. The key feature of this automatic cycle is rapid blood pressure cuff bleed down from an initial setting until systolic (diastolic) pressure is encountered followed by a short repressurization and slow bleed, long enough to permit accurate systolic (diastolic) pressure determination. The system includes a pressure reservoir which bleeds the cuff through a precision needle valve; a solenoid valve which permits rapid pressurization from the reservoir; and a pressure sensor which provides information for bleed rate and set point controls. Korotkoff sound signals from a microphone in the blood pressure cuff (not part of the system) provide decision information to the digital control system. The system completed a series of engineering tests using simulated Korotkoff sound inputs. The system performed successfully in all cases and was stable over an extended period of time.

Fogal, G. L.↗
NASA NTRS1971

IMBLMS phase B4, additional tasks 5.0. Microbial identification system

A laboratory study was undertaken to provide simplified procedures leading to the presumptive identification (I/D) of defined microorganisms on-board an orbiting spacecraft. Identifications were to be initiated by nonprofessional bacteriologists, (crew members) on a contingency basis only. Key objectives/constraints for this investigation were as follows:(1) I/D procedures based on limited, defined diagnostic tests, (2) testing oriented about ten selected microorganisms, (3) provide for definitive I/D key and procedures per selected organism, (4) define possible occurrences of false positives for the resulting I/D key by search of the appropriate literature, and (5) evaluation of the I/D key and procedure through a limited field trial on randomly selected subjects using the I/D key.

Source record↗
NASA NTRSDate not supplied

HERMeS Thruster Magnetic Field Topology Optimization Study: Plasma Plume Results

NASA’s Hall Effect Rocket with Magnetic Shielding (HERMeS) 12.5-kW Technology Demonstration Unit-1 (TDU-1) has been the subject of extensive technology maturation in preparation for flight system development. The magnetic optimization study aims to explore and investigate alternate magnetic field topologies. Four candidate magnetic field topologies that reduce the effectiveness of the shielding along the discharge channel walls with the intent to also reduce the erosion rates along the front pole covers were designed. Three of the four candidate magnetic field topologies (B1, B2, and B4) have been manufactured and were subjected to an extensive test campaign that included laser induced fluorescence (LIF), performance, stability, wear, and plume characterization. In Phase I, LIF measurements along the discharge chamber centerline found that upstream retraction of the thruster’s peak magnetic field does result in an upstream shift of the acceleration zone, but the magnitude of the shift does not correspond one-to-one to the shift in the location of the peak radial magnetic field magnitude. Phase II test segment results found that at a normalized thruster magnetic field setting of 1, the thruster performance and discharge current oscillations were very similar for configurations B0-B2. Also in Phase II abbreviated wear tests found that average inner front pole cover erosion rates for configuration B1 were approximately 65% of those at B0, and the average erosion rates for configuration B2 were approximately 35% of those at B0. This paper reports on the detailed plasma plume mapping results for configurations B0-B4. Faraday probe results indicate that, at 600 V operation, the plume divergence increased slightly for the B4 configuration when compared to B0-B2. Wien filter spectrometer results found that at 600 V, lower multiply-charged species fractions were attained as the thruster transitioned from configurations B0 to B4. Finally, retarding potential analyzer results found that at 600 V operation and at angles above 60,˚ significantly lower high-energy ion content was found for configurations B2 and B4 when compared to B0 and B1.

Electric propulsion,.Hall thruster, laser diagnost↗
NASA NTRS2019

HERMeS Thruster Magnetic Field Topology Optimization Study: Performance, Stability, and Wear Results

NASA's Hall Effect Rocket with Magnetic Shielding (HERMeS) 12.5kW Technology Demonstration Unit-1 (TDU-1) has been the subject of extensive technology maturation in preparation for flight system development. The TDU-1 thruster implements a magnetically shielded field topology and has demonstrated the elimination of the discharge channel erosion as a life limiting mechanism. Extensive wear testing the TDU Hall thrusters has identified the thruster front pole covers as the next life limiting component. This effort aims to explore and investigate alternate magnetic field topologies to assess whether reductions in the front pole cover erosion can be attained while still maintaining very low erosion rates on the discharge channel walls. Four candidate magnetic field topologies that reduce the effectiveness of the shielding along the discharge channel walls with the intent to also reduce the erosion rates along the front pole covers were designed. Three of the four candidate magnetic field topologies (B1, B2, and B4) have been manufactured and were subjected to an extensive test campaign that includes laser induced fluorescence (LIF), performance, stability, wear, plume, and thermal characterization. In Phase I, LIF measurements along the discharge chamber centerline found that upstream retraction of the thruster's peak magnetic field does result in an upstream shift of the acceleration zone but the magnitude of the shift does not correspond one-to-one to the shift in the location of the peak radial magnetic field magnitude. Phase II test segment results found at a normalized thruster magnetic field setting of 1, the thruster performance was very similar for all configurations. Discharge current waveforms ripple data indicated that configurations Bo, B1, and B2 has similar oscillatory profiles with the B2 configuration transitioning to higher oscillatory mode at 400V instead of the 450V observed for configurations B0 and B1. Configuration B4 ripple data indicates that the thruster was operating in a very oscillatory mode above 350V. Inner front pole cover erosion rates for configuration B1 were approximately 65% relative to B0 and the erosion rates for configuration B2 were 40% relative to B0. Analysis of the performance, stability, and wear test results of configurations B0, B1, B2, and B4 indicates that configuration B2 may present an alternative option for B0 because it mostly maintained the same performance and stability as configuration B0 but with 40% of the inner front pole cover erosion rate.

Kamhawi, Hani↗