A multiple wire magnetostrictive delay line for improved signal and reduced reflections

Abstract

Abstract. The amplitude of the output signal per unit of cross sectional area of a magnetostrictive delay line decreases for increasing wire diameter due to the skin effect. For a fixed area a large output signal can be obtained by using a number of thin wires. An additional advantage is the reduced influence of inhomogeneities along the wires. Reflections in this multiple wire delay line can be reduced firstly by means of interference by half ends free, and/or secondly through spreading out the reflections by shifting the ends of the wires with respect to each other. A simple magneto-acoustic position measurement system using a multiple wire delay line and one single transmitting/receiving coil is demonstrated. Figure 1. Scheme of magnetostrictive delay line (a), the current in the receiving coil (c). The time delay is given by the ratio of the distance between the coils and the velocity of sound. fixing half ofthe number of wires to a mass and leaving the other pulse in the transmitting coil (b) and the amplified output signal conductor and erf is the error function given by the relation erf U = 2 / f i 1 ” exp- t2 dt.