Design of Shielded Solenoids for Charged Particle Beam Applications

Abstract

Focusing solenoids for accelerators and other charged particle beam applications usually have general requirements: focusing strength, stray field, eddy current losses and specific requirements. For industrial applications discussed in the paper, conventional resistive solenoids can be used, which have specific requirements include maximum operation current, minimum inductance or impedance. For high energy applications, superconducting focusing solenoids have been used widely [(T. Yang et al ., 2016), (G. Davis et al. , 2007)], which will have different design requirements. In contrast to a single quadrupole magnet, solenoid magnets can provide simultaneous focusing in both x- and y-directions. However, the focusing strength of solenoids is relatively low compared to quadrupoles due to the second order field effects (E. Muro et al. , 1990). But for low energy industrial application, solenoid magnets will be one of the cost-effective solutions. This paper proposes several design options to improve the performance of conventional resistive focusing solenoids. These design options include adding bucking coils to limit the stray fields, splitting the main coil to reduce the total impedance of the coils and implementing passive shielding layers to minimize the stray field and the effects of external disturbances simultaneously. Simulation results and experimental test data will be presented.