Physical Sciences

Steady-State Thermal Test Methodology

This innovation provides the following thermal properties data from a single steady-state test run: the effective thermal conductivity value (ke) for the full temperature difference, and multiple thermal conductivity values (λ) for intermediate temperatures. The test specimen (or material) is instrumented with one or more intermediate temperature sensors to allow the calculation of the multiple λ data points within the material and through its thickness. The methodology is particularly effective when coupled with any of the cryogenic boil-off calorimetry instruments (cryostats) developed by the Cryogenics Test Laboratory at NASA-KSC.

Posted in: Briefs, TSP, Physical Sciences, Test equipment and instrumentation, Test procedures, Thermal testing
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Silicon Carbide Power Processing Unit for Hall Effect Thrusters

A high-efficiency, rad-hard, 3.5-kW SiC power supply was developed for the power processing unit (PPU) of Hall effect thrusters. This work specifically targets the design of a PPU power supply for the HiVHAC (High Voltage Hall Accelerator) thruster. The PPU power supply under development utilizes components that were irradiated under TID (total ionizing dose) conditions to greater than 3 Mrad with little to no change in device performance.

Posted in: Briefs, TSP, Physical Sciences, Power electronics, Power electronics
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Intensity-Calibrated Hydrogen Flame Spectrum

The National Aeronautics and Space Administration (NASA) uses large quantities of liquid hydrogen and has expended significant effort in the development, testing, installation, and maintenance of hydrogen fire detectors based on ultraviolet, near-infrared, mid-infrared, and/or far-infrared flame emission bands. Yet, prior to this work, there was no intensity-calibrated broadband hydrogen-air flame spectrum in the literature, making it difficult to compare the merits of different radiation-based hydrogen fire detectors.

Posted in: Briefs, TSP, Physical Sciences, Fire detection
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Exciting and Detecting Electromagnetic Energy in a High-Temperature Microwave Cavity

There is a need to perform accurate, high-temperature, complex dielectric constant measurements at microwave frequencies on materials, such as those on the surface of Venus (surface temperature 460 °C). One approach is to excite and detect a TE10n mode resonance in a waveguide cavity heated in a high-temperature furnace. The standard way is to use commercial high-temperature transition adapters attached to cavity end plates containing small iris holes that weakly couple microwave energy into and out of the cavity. These high-temperature transition adapters are not simple to make, and are rather large in size. The addition of the transition adapter units to the waveguide cavity leads to a long combined system that in many cases makes it difficult, if not impossible, to insert in conventional high-temperature furnaces.

Posted in: Briefs, TSP, Physical Sciences
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Hollow aErothermal Ablation and Temperature (HEAT) Sensor for Tracking Isotherm Through TPS Material

The Hollow aErothermal Ablation and Temperature (HEAT) sensor is a multifunction sensor designed to track an isotherm by making an independent transient measurement at a defined location in the sensor that is equal to the temperature at which its constituent materials char. By this same operating principle, the HEAT sensor tracks the transient char depth progression within a thermal protection system (TPS) material. In the case of a material that sublimes (such as Teflon), or when the aerothermal environment induces steady-state ablation, the HEAT sensor measures material ablation directly.

Posted in: Briefs, TSP, Physical Sciences, Sensors and actuators, Sensors and actuators, Insulation
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Hydrogen Measurement in a Cryogen Flow Stream Reduces Waste of Helium

The purpose of this research was to develop an improved method for measuring hydrogen concentrations in a cryogen flow stream to minimize helium waste during the purge process. Currently, this type of measurement is performed manually with a sniffer, and involves obtaining periodic measurements that are not accurate or repeatable and do not optimize the conservation of hydrogen. The goal of this project was to create an autonomous real-time method for continuously measuring hydrogen that potentially offers not only cost saving advantages by conserving expensive resources that are used for purging, but also for providing an additional safety mechanism to monitor hydrogen in a cryogenic flow stream.

Posted in: Briefs, Physical Sciences, Sensors and actuators, Sensors and actuators, Sustainable development, Energy conservation, Propellants
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Noncontact DC and AC Magnetostrictive Current Sensor

At the time of this reporting, there have been no effective methods of monitoring current in conductors in space without breaking the circuit or making contact with the conductor. In space, reliability rules all designs, and breaking a circuit to insert a sensor to monitor current would reduce reliability of the system. Hall effect sensors provide a noncontact DC measurement technique, but they are relatively expensive and not rugged enough for the space environment.

Posted in: Briefs, Physical Sciences, Sensors and actuators, Sensors and actuators
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Method and Apparatus for Determining Propellant Mass in Microgravity by Capacitance Measurements

Propellant mass gauging in microgravity has posed a challenge for decades. Various methods have been applied, including ultrasonic, capacitance probes, point level sensors, thermal detectors (thermistors, thermocouples, etc.), Michelson interferometry, and nuclear devices. All have problems in terms of how to provide accurate measurements irrespective of the fluid orientation in the tank.

Posted in: Briefs, Physical Sciences, Analysis methodologies, Propellants, Test equipment and instrumentation
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Preparation, Planning, and Concept Demo of a Technique to Find ≈7-to-10-m Near Earth Asteroids

A paper describes a new technique designed to increase significantly the sensitivity for finding and tracking small, dim, and fast-moving near Earth asteroids (NEAs). The technique relies on a combined use of a novel data processing approach and a new generation of high-speed CCD cameras. These new cameras have very low readout noise (≈le–) and allow taking short exposures of moving objects at high frame rates, effectively “freezing” their motion on the CCD. A long-exposure image is synthetically created as if the telescope were tracking the object with a significantly higher SNR — an approach called “synthetic tracking.” By changing the shift/add vector, multiple dim objects moving in different directions can be detected in the same data set.

Posted in: Briefs, TSP, Physical Sciences, Imaging, Imaging and visualization, Imaging, Imaging and visualization, Data management
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Strobing to Mitigate Vibration for Display Legibility

This method mitigates the motion blur introduced when a display, and/or the operator reading it, is undergoing vibration (e.g. during the launch phase of spaceflight). If both the operator and the display are undergoing vibration, their respective impulses need not be in phase. This mitigation occurs when the display is illuminated at a strobing rate that corresponds with the frequency of the vibration. This can be done either by strobing the ambient illumination in the environment (e.g., if the operator is reading a reflective surface display), or by strobing the display itself (e.g., strobing the LED backlighting of an electronic display).

Posted in: Briefs, TSP, Physical Sciences, Displays, Displays, Vibration, Vibration
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