| 摘要 |
A transducer for an acoustic logging tool includes a liquid-filled cavity formed by a substantially rigid housing portion of the tool and having a resilient barrier member disposed between liquid in the wellbore and the liquid in the cavity. A magnetic field extends transversely through the cavity and a member, which may comprise a rigid plate, a flexible member or a quantity of electrically conductive liquid trapped between flexible membranes, is disposed in the cavity for movement normal to the magnetic field. A voltage is generated in response to movement of liquid in the cavity which is proportional to the velocity of the plate or member, or the velocity of the conductive liquid, the length of the conductive path and the intensity of the magnetic field in accordance with the principles of the Lorentz force. Alternatively, electrical current may be caused to flow through the plate, the flexible member or the conductive liquid, thereby causing the Lorentz force to displace the plate, member or conductive liquid to provide a unidirectional pressure wave for generation of flexural waves in the wellbore.
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