Contactless magnetic temperature sensors for turbo-molecular pumps

A magnetic sensor for non-contact measurement of the temperature of a spinning device is studied in the present work. This sensor specifically applies to the control and safe operation of turbo-molecular pumps. The sensing element consists of a “magnetic capsule”, composed of a quasi-ideal permanent magnet with high Curie temperature and a Fe–Ni alloy cylinder, mounted on the rotor, and a detecting coil stuck on the pump frame, where a voltage pulse is induced at every turn by the passage of the capsule. It is demonstrated that the sensor can be designed so as to have a linear voltage-versus-temperature behaviour, where the signal strength depends on the distance between the revolving magnet and a fixed pickup coil and is independent of rotor speed.