Tech Briefs

Portable Friction Stir Welding Machine

The machine is capable of butt-welding aluminum 1,100 workpieces 1/8 in. (≈3 mm) thick. Marshall Space Flight Center, Alabama A preliminary design of a portable friction stir welding (FSW) machine for use in space has been developed. The in-space FSW machine takes the form of a handheld router tool that is historically used in woodworking applications. With the design of the in-space FSW machine, the FSW tool is directly connected to the motor shaft while the motor is mounted to a small frame that supports the tool. The frame has handlebars that allow the operator to grasp the welder and maneuver it along a desired weld path. The key enabler of the in-space FSW machine is an innovative FSW tool design. The FSW tool is a fixed shoulder-to-shoulder bobbin tool that self-aligns and adjusts to the workpiece. The self-aligning and adjusting FSW (SAA-FSW) tool floats freely in the vertical direction, thereby eliminating any external axial load on the machine or operator. The total weight of the in-space FSW machine is 73 lb (≈33 kg), and it only requires one operator. The machine is capable of butt-welding aluminum 1,100 workpieces 1/8 in. (≈3 mm) thick.

Posted in: Manufacturing & Prototyping, Briefs

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Multimode, Fiber-Coupled, Tungsten Silicide, Superconducting Nanowire Single-Photon Detector Array

Amorphous WSi allows a much greater active area due to lower incidence of nanowire constrictions. NASA’s Jet Propulsion Laboratory, Pasadena, California The superconducting nanowire single-photon detector (SNSPD) arrays created in this innovation were fabricated using a WSi nanowire process. A gold mirror layer is deposited on an oxidized silicon wafer, and amorphous-state WSi is sputtered from a compound target at a thickness of 5 nm. The WSi nanowire is embedded at the center of a three-layer vertical optical cavity consisting of two silica layers and a titanium oxide anti-reflective coating. The layer thicknesses were chosen, on the basis of simulations and measured material parameters, to optimize efficiency at the target communication wavelength of 1,550 nm, and to minimize the polarization dependence of the detector response.

Posted in: Manufacturing & Prototyping, Briefs

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Sidewall Passivation of GaN Avalanche Photodiodes via Atomic Layer Deposition

Atomic layer deposition is explored as a sidewall passivation method for mesa-isolated gallium nitride. NASA’s Jet Propulsion Laboratory, Pasadena, California The visible-blind detection of UV light has important applications in planetary imaging and spectroscopy, astronomy, communications, and defense-related imaging. Future instruments for imaging in the ultraviolet will require improvements in detector capabilities. An all-solid-state ultraviolet detector will enable substantial improvements in mass, volume, complexity, power, and robustness compared with conventional image-tube-based technologies. One new class of solid-state UV detectors includes those based on the gallium nitride (GaN) family of materials. The electronic passivation methods described here are one promising way to produce detectors with the required low dark current characteristics, and show a significant improvement over current state-of-the-art passivation methods. These methods will contribute to a next-generation solar-blind, solid-state UV detector for a wide range of space-based UV instruments.

Posted in: Manufacturing & Prototyping, Briefs

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A Portable, Projection Focusing Schlieren System

Heating, ventilation, and air conditioning systems can be monitored using this system, especially those used in commercial kitchens and industrial ventilation. John H. Glenn Research Center, Cleveland, Ohio A new type of projection schlieren camera system (schlierenscope) is more portable, easier to align, and more versatile than existing systems. The schlierenscope is a projection focusing schlieren camera system that can acquire images of shock waves, vortices, gas jets, and other disturbances that create gradients in the refractive index of a transparent medium. These gradients appear as streaks (called schlieren in German) in the resulting image. Thus, a schlierenscope is an apparatus for looking at disturbances in transparent media. The schlierenscope constructed in the project utilizes fast strobes that freeze motion and capture images with a scientific CCD (charge-coupled device) camera. The schlierenscope is unique among schlieren instruments because all of the critical controls are contained within the instrument housing.

Posted in: Test & Measurement, Briefs

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Cryogenic and Non-Cryogenic Optical Liquid Level Instrument for Stratified Conditions

Marshall Space Flight Center, Alabama Typical cryogenic tank metering systems use a series of thermocouple, RTD, or other temperature or resistive devices in a rake or array configurations. Since these operate using the thermal change between the liquid and gas fluid phases, they are limited by thermal latency (the time it takes the sensing element to respond to the temperature). In addition, cryogenic fluids often create a volatile boundary or sloshing layer. This layer causes uncertainties of the true fluid boundary in a tank. Finally, accuracy and resolution are determined by the number of sensing segments used. These are typically tied to individual data channels, which puts a strain on data acquisition systems to achieve continuous and high-accuracy values.

Posted in: Test & Measurement, Briefs

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Low-Pressure Ion Chromatography for Planetary Exploration

NASA’s Jet Propulsion Laboratory, Pasadena, California Ion chromatography is the state-of-the-art technique for anion separation and analysis on Earth, but it typically requires a large, powerful pump to operate at high pressures in order to speed up analysis time. The weight and power requirements of the pump interfere with creating an ideal instrument for flight. The solution is to run the ion chromatography system at low pressure to allow the use of a smaller, lower-power pump for flight, but at the expense of longer analysis time.

Posted in: Test & Measurement, Briefs

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Ultra-Low-Maintenance Portable Ocean Power Station

These fuel cell systems can be used for remote power generation, transportation applications, or in offshore wells. NASA’s Jet Propulsion Laboratory, Pasadena, California The goals of this research are to develop a relatively inexpensive, compact, and modular power package for deep offshore oil drilling or other undersea applications that provides 2 to 5 MW electricity, minimal maintenance, and at least 30 years of life.

Posted in: Physical Sciences, Briefs

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