A new alignment method for HIMM magnetic field measurement system.

The Heavy Ion Medical Machine (HIMM) is China's first heavy ion accelerator specifically for cancer treatment. To minimize the uncontrollable beam orbit and beam loss, the HIMM accelerator magnets require the condition of stringent field uniformity. The best way to examine whether the actual field is consistent with the design or not is to perform an accurate and reliable measurement on the magnetic field, which requires the accurate alignment of the magnetic field measurement system as the prerequisite. This research adopts the alignment of a Hall probe mapping system, long coil integral system and harmonic coils system. Firstly, the preliminary test launched at the HIMM is described. Then, a new alignment method is developed to improve the positioning accuracy and performance of magnetic field measurement system. The experimental results show that the alignment accuracy (maximum deviations) of all components of each magnetic field measurement system is higher than 0.1 mm, which satisfies the requirements for the positioning accuracy of high-precision magnetic field measurement system. [ABSTRACT FROM AUTHOR]