Multi-sensor Acoustic Tomograph for Gas Mixture Content Monitoring

Helium is a common coolant in the modern superconducting magnets construction. One of the most important problems related to such systems is the protection of the human personnel against the uncontrolled spilling of the helium leading to oxygen deficiency syndrome. The detection of a helium leak is possible either by slow electrochemical detectors or by modern fast acoustic detectors. An acoustic measurement uses relation between the helium content and sound velocity in gas mixture. The oxygen content can be evaluated through helium content measurement. The tomographic measurement can produce the spatial distribution of helium and temperature. In the paper a prototype of the multi-sensor acoustic tomograph was presented. The instrument uses an array of ultrasonic transducers and it is capable of reproduction of spatial distribution of helium stream.