Magnetic field strength and temperature-dependent calibration system of Hall probe for the HEPS-TF cryogenic permanent magnet undulator

Abstract

High energy photon source test facility (HEPS-TF) has manufactured a three-dimensional Hall probe to measure the cryogenic permanent magnet undulator (CPMU). Since the operating environment of the CPMU is the subcooled liquid nitrogen (85K), the temperature of the Hall probe will have a decrease of several degrees while carrying out the local magnetic measurement. We established a magnetic field strength and temperature-dependent calibration system to calibrate the Hall probe. The magnetic field strength of the Hall probe was calibrated by a standard dipole electromagnet and a nuclear magnetic resonance Tesla meter (NMR). The temperature of Hall probe was controlled by a control system which can modulate temperature from $$0^{\circ }$$ C to $$30^{\circ }$$ C. A new homemade Hall probe has finished the temperature-dependent ( $$0^{\circ }$$ C to $$30^{\circ }$$ C), magnetic field strength (-1.2 to 1.2 T) and angle error calibration at this new calibration system. The temperature correction error is less than 0.045%. The calibration error of magnetic field strength is less than 1.5 Gs. The RMS calibration error of Hall sensors angle matrix is less than 5.1E-5. The magnetic field strength and temperature-dependent calibration system including a standard dipole electromagnet, a temperature regulation system, an NMR and a five-dimensional Hall bench was established. The detailed magnetic field strength and temperature-dependent calibration system is introduced and the results of the calibrations are presented.