Frequency response characterization of ironless inductive position sensors with long cables

Abstract

The two linear position sensors used to determine the position of the European Organization for Nuclear Research; Large Hadron Collider collimator’s jaws with respect to the beam are the linear variable differential transformer and the ironless inductive position sensor. The latter was designed as an alternative to the former since the linear variable differential transformer exhibits a position error in magnetic environments. The ironless inductive position sensor is an air cored, high-precision linear position sensor, which is by design immune to external DC or slowly varying magnetic fields. Since the ironless inductive position sensor is required to have no on-board electronics, the raw signal has to be carried through long cable lengths and this may lead to performance degradation. This paper focuses on a set of experimental measurements conducted to assess the ironless inductive position sensor’s sensitivity at different frequencies with long cable lengths. This is critical for the sensor`s correct operation in the Large Hadron Collider`s collimators. Furthermore, to gain a better understanding, the ironless inductive position sensor’s frequency response is compared with a commercial off-the-shelf linear variable differential transformer.