Field mapping system for KIRAMS-30 cyclotron magnet

Abstract

This paper presents a Hall-probe mapping system for measuring a cyclotron magnet. The system fabricated for the 30-MeV cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The Hall probes were mounted on a precision mechanical rotational stage and mapped the magnetic field in a cylindrical coordinate system. The mapping system used the "flying" mode field mapping method to reduce the data-acquisition time. The time required for mapping the whole gap-area of the cyclotron magnet was similar to 75 minutes. The relative random fluctuation error during the entire mapping process was less than +/- 0.01 %. The cyclotron magnet was corrected using the measured data for the magnetic field. After the correction, the total phase excursion of the cyclotron was less than +/- 12 degrees, which is within the total phase excursion tolerance of +/- 20 degrees.