Abstract: A variable reluctance pickup system for steel string musical instruments is described which provides a highly asymmetrical magnetic field for preferentially sensing and generating electrical signals responsive to string vibrations perpendicular to the string plane. The described pickup system includes individual magnetic circuits with pole pieces, and a sensing coil for each string. The pickup system further includes special planar poletip faces which modify the spatial configuration of the magnetic fields emanating from the polepieces to render the pickup system relatively insensitive to "bending" of a string from its normal quiescent position. The described pickup system is designed to provide electronically amplified musical instruments with tonal characteristics similar to the tonal characteristics of acoustic string instruments.

Abstract: A single face, variable reluctance pickup for steel string musical instruments is described which provides a highly asymmetrical magnetic field for preferentially sensing and generating electrical signals responsive to string vibrations perpendicular to the string plane. The described pickup features a single permanent bar magnet, common shaping faces, oriented parallel the string plane and perpendicular the strings and a plurality of sensing circuits having cores which magnetically and mechanically couple the shaping faces and the bar magnet. The described pickup provides a magnetic field in the string plane having a large flux gradient perpendicular the string plane and a minimum flux gradient parallel the string plane. The pickup is insensitive to "bending" and provides electronically amplified musical instruments with tonal characteristics similar to the tonal characteristics of acoustic string instruments.

Abstract: A high power density continuous wave (c. w.) gas dynamic laser system is described which includes a non-equilibrium plasma jet for generating excited gaseous species having high vibrational temperature and low gas temperature. Gas flow through the plasma jet is reduced to highly turbulent subsonic flow by an expanding nozzle. Lasing in an optical cavity oriented transversely with resspect to the flow of the gaseous plasma extracts vibrational energy from the excited gaseous species as the emerge from the expansion nozzle.The described system also includes, immediately upstream from the optical cavity, an injection system which introduces and uniformly mixes a lasing gaseous species into the highly turbulent subsonic gaseous plasma flow from the plasma jet. Gas sweeps are established in the arms of the optical cavity to cool and sweep high temperature unexcited gas species therefrom in order to reduce absorption in the optical cavity.