Research on a Superconducting Magnetic Flux Concentrator for a GMI-Based Mixed Sensor

A magnetic concentrator (MC) is often used to increase the performance of traditional magnetic sensors. A superconducting MC has been proven to be high powered when integrated with a field sensor. Such concentrators are often designed as a square loop shape with a narrow constriction. When an external field is applied, a superconducting current will be induced that flows in the loop. The self-field in the local area of the narrow constriction is much higher than the applied field, which can be detected by a field sensor. In this paper, a superconducting MC is described, and the amplified magnetic flux density is calculated. Magnetooptical experiments are performed on three samples to better understand the phenomenon. The magnetic properties of the concentrator are investigated in the field of 0.1-300 Oe. The maximum magnetic gain of our three samples is 55 as given by the magnetooptical measurements. Considering the great progress made in giant magnetoimpedance (GMI) film materials, a GMI-based mixed sensor with a well-designed superconducting MC is very promising for achieving a high resolution for low-field detection.