Observations of Quasi-nonradiating wave sources in one dimension

Abstract

A nonradiating wave source is one that drives waves over a region of a medium, where no waves propagate outside the region due to complete destructive interference at the boundary. This thesis describes the first observations of an acoustical source of this type. Physical observations are made with a current-carrying wire that is transversely driven by several types of magnetic field distributions. The wire glows as a result of the current, and the wave pattern can be observed due to the cooling caused by the motion of the wire. The predicted standing wave response in the source region is confirmed. Numerical simulations of a one-dimensional mass-and-spring lattice show that dissipation, nonuniformity, and nonlinearity each cause radiation to escape from the source region. The radiation amplitude relative to the standing wave amplitude is substantially reduced for sources that are distributed over a region rather than lumped over the same region. In addition, it is possible to make adjustments to the drive parameters to substantially minimize the radiation