longitudinal quadrupole[‚län·jə′tüd·ən·əl ′kwäd·rə‚pōl]
A sound source resulting from a variation of a component of the velocity of matter in a direction parallel to the velocity component.
An electric or magnetic quadrupole which produces a field equivalent to that of two equal and opposite electric or magnetic dipoles separated by a small distance parallel to the direction of the dipoles. Also known as axial quadrupole.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.