Special Coverage


Plasmoid Thruster for High Specific-Impulse Propulsion

A report discusses a new multi-turn, multi-lead design for the first generation PT-1 (Plasmoid Thruster) that produces thrust by expelling plasmas with embedded magnetic fields (plasmoids) at high velocities. This thruster is completely electrodeless, capable of using in-situ resources, and offers efficiencies as high as 70 percent at a specific impulse, Isp, of up to 8,000 s. This unit consists of drive and bias coils wound around a ceramic form, and the capacitor bank and switches are an integral part of the assembly. Multiple thrusters may be ganged to inductively recapture unused energy to boost efficiency and to increase the repetition rate, which, in turn increases the average thrust of the system.

Posted in: Mechanical Components, Briefs


Using Digital Radiography To Image Liquid Nitrogen in Voids

X-ray motion pictures show draining and filling caused by cryopumping. Digital radiography by use of (1) a field- portable x-ray tube that emits low- energy x rays and (2) an electronic imaging x-ray detector has been found to be an effective technique for detecting liquid nitrogen inside voids in thermal- insulation panels. The technique was conceived as a means of investigating cryopumping (including cryoingestion) as a potential cause of loss of thermal insulation foam from space-shuttle external fuel tanks. The technique could just as well be used to investigate cryopumping and cryoingestion in other settings.

Posted in: Physical Sciences, Briefs


Multiple-Parameter, Low-False-Alarm Fire-Detection Systems

Compact, low-power systems detect fires reliably. Fire-detection systems incorporating multiple sensors that measure multiple parameters are being developed for use in storage depots, cargo bays of ships and aircraft, and other locations not amenable to frequent, direct visual inspection. These systems are intended to improve upon conventional smoke detectors, now used in such locations, that reliably detect fires but also frequently generate false alarms: for example, conventional smoke detectors based on the blockage of light by smoke particles are also affected by dust particles and water droplets and, thus, are often susceptible to false alarms. In contrast, by utilizing multiple parameters associated with fires, i.e. not only obscuration by smoke particles but also concentrations of multiple chemical species that are commonly generated in combustion, false alarms can be significantly decreased while still detecting fires as reliably as older smoke-detector systems do.

Posted in: Physical Sciences, Briefs, TSP


Direct Coupling From WGM Resonator Disks to Photodetectors

Output coupling of light from a whispering- gallery-mode (WGM) optical resonator directly to a photodetector has recently been demonstrated. By “directly” is meant that the coupling is effected without use of intervening optical components. Heretofore, coupling of light into and out of WGM resonators has been a complex affair involving the use of such optical components as diamond or glass prisms, optical fibers, coated collimators, and/or fiber tapers. Alignment of these components is time-consuming and expensive.

Posted in: Physical Sciences, Briefs


Dog-Bone Horns for Piezoelectric Ultrasonic/Sonic Actuators

Relative to other shapes, the dog-bone shape offers better performance. A shape reminiscent of a dog bone has been found to be superior to other shapes for mechanical-amplification horns that are components of piezoelectrically driven actuators used in a series of related devices denoted generally as ultrasonic/sonic drill/corers (USDCs). The first of these devices was reported in “Ultrasonic/Sonic Drill/Corers With Integrated Sensors” (NPO-20856), NASA Tech Briefs, Vol. 25, No. 1 (January 2001), page 38. The dog-bone shape was conceived especially for use in a more recent device in the series, denoted an ultrasonic/ sonic gopher, that was described in “Ultrasonic/Sonic Mechanisms for Drilling and Coring” (NPO-30291), NASA Tech Briefs, Vol. 27, No. 9 (September 2003), page 65. The figure shows an example of a dog-bone-shaped horn and other components of an ultrasonic gopher.

Posted in: Manufacturing & Prototyping, Briefs


Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites

A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon- carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to reentry into the atmosphere of the Earth.

Posted in: Manufacturing & Prototyping, Briefs, TSP


NASA Briefs

The Web- based Real- Time Asset Monitoring (RAM) module enables emergency personnel to monitor and analyze data in the event of a natural disaster. The software can manage many disparate sources of data - including streaming data - within a facility, city, or county. Learn more here.

Posted in: Blog