دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a tightly banded scroll of special steel that vibrates when a magnetic field is applied to it. The vibration of the scroll sets off a transmitter, which is alternately switched on and off at 15 to 60 times per second. The transmitter causes compressional sound waves to travel through the formations surrounding the borehole. Each formation material will exhibit its own characteristic effect on the elastic wave propagation.