Accurate Low Magnetic Field Measurements on Superconducting Coils

Abstract

Sensitive Hall effect probes, which are now commercially available, have been used to measure the magnetic fields generated by superconducting coils. The sensitivity has been measured to be 0.080 V/kG-A at 4.2°K. Field resolution at IH=100 mA using a Keithley 149 millimicrovoltmeter is 12.5 mG. The probe calibration is linear from 0–6 kG which is the range of interest for several experiments which are described. Probe performance is demonstrated by measurements of the residual field of a NbZr solenoid, the magnetization of vapor-deposited Nb3Sn cylinders, and the uniformity of a superconducting magnet for a traveling wave maser.