| Popis: |
A piston‐type magnetostrictive transducer consisting of a scroll‐wound tube 12 in. long, 1.25 in. in diameter, and of 0.125‐in. wall thickness was constructed from 0.008‐in. Nickel 200 sheet and fitted with toroid‐wound and solenoid‐wound drive coils. This prototype device was evaluated using both conventional and orthogonal modes of excitation. Electrical impedance measurements at low drive levels showed an increase in the electromechanical coupling coefficient with orthogonal excitation. Power tests were conducted with output power levels up to 50 W/cm2 of active core area by driving the piston into a tuned ceramic dummy load. Device efficiency in excess of 50% was obtained at 5 W/cm2 output power. As the output power was increased, orthogonal excitation consistently provided higher efficiency and linearity than conventional excitation. Device linearity improved with increasing drive level for the orthogonal tests. Self‐biased excitation was obtained by driving the two coils plus a pair of diodes in par... |
