NEW SELF-CONTAINED DEEP-TOWED PROTON MAGNETOMETER SYSTEM

A new compact deep-towed proton magnetometer system was developed and tested in 11 cruises around the Japanese Islands. The pressure case to wed by a steel wire rope on the winch carries a portable proton magnet ometer, a depth meter and their power supplies. The magnetometer senso r is connected to the pressure case with an armored cable 15 m long. T he system automatically measures the total geomagnetic field intensity and the towing depth. It also stores the observed data on the interna l digital memories within the instruments. This self-contained system enables us to make deep-towed observations up to a depth of 6000 m wit hout an expensive armored towing cable. Furthermore, the simple system facilitated the operation and the production, and it reduced the cost s. In our experiments, we successfully collected a maximum of 13 hours data and recorded a maximum towing depth of 3667 m. Some observed dee p-towed data showed detailed information about magnetic anomalies, whi ch could not be detected by surface-towed magnetometers. We will here explain the system with the results of two experiments and show that i t is very useful for deep-towed magnetic observations.