Engineering topics
Publications and source records attributed to Murphy, A. J..
Actuator is portable and can be used in high-temperature (over 500 C) environments by incorporating tungsten metal film and quartz window. Actuator can be triggered when it is not directly in laser beam path by utilizing fiber optics. It is advantageous for remotely switching ultra-high voltage systems.
This paper describes a pyrotechnic ignition model based on transient heat conduction from a heated bridgewire to a pyrotechnic that is placed in contact with it. The boundary condition used at the interface was a thermal contact conductance estimated at 31,200 W per sq m-K between the wire and the pyrotechnic. Ignition was assumed to occur when a 2.5-micron layer of pyrotechnic next to the bridgewire reached a critical ignition temperature. The times to ignition predicted by this model for constant current firings were in good agreement with experimentally observed times to fire at 3.5- and 5-ampere current levels and ambient temperatures from 144 K to 366 K.
An optically actuated mechanical mover adapted to be moved from an ambient position to an active position, is disclosed. The mechanical mover essentially comprises a piston/cylinder arrangement including a piston that is contained within an internal cylindrical chamber of a housing. The cylindrical chamber is configured to permit the piston to be moved for the length of the chamber as a work stroke. A lock pin extending through the piston, and diametrically opposed walls of the chamber housing, retain the piston in the ambient position at one end of the chamber. An actuator for producing a pressure or shock wave that drives the piston is positioned at the end of the chamber corresponding to the piston ambient position.
Investigation of hot wire dynamic behavior under high-current heating aimed at a better understanding of the ignition process, using high-speed photographic techniques for visual observation of the bridgewire itself during high current heating. Tests were conducted with Tophet A bridgewires in an air environment, as well as in a cell of distilled water at room temperature, and with a boron-potassium perchlorate-Viton pyrotechnic against the bridgewire behind a Plexiglas window.
Low voltage capacitor discharge firing circuit to initiate hot bridgewire squibs for spacecraft applications
Design procedure for low voltage capacitor discharge circuits to trigger electroexplosive devices in aerospace vehicles