Development of bismuth metallic hall sensors for the HL-2A tokamak magnetic measurements

100 nm bismuth-based Hall sensors have been developed on the HL-2A tokamak recently. This paper reviews the process of manufacturing a Hall sensor with high sensitivity, including material selection, craft optimization, and platform testing. Magnetron sputtering and SiO2 glass substrate are proposed to reduce the thickness error. The sensitivity of the sensor is obtained by linear fitting, and the calibration accuracy is better than +/- 1 % when the magnetic field range is greater than 3 mT. The housing and mounting position of the Hall sensor are designed so that they can be compared with the pick-up coils in the upcoming discharge experiment.