Speaker
Description
Next-generation storage rings require low emittance and high brilliance, and their quadrupole magnets must provide both high magnetic gradients and stringent multipole field quality. Conventional electromagnetic quadrupoles consume substantial electrical power and require cooling systems because of Joule heating. In this study, a permanent magnet quadrupole (PMQ) that generates its magnetic field without an excitation power supply and allows the gradient to be varied mechanically was designed.
Starting from a two-dimensional pole shape and an end-edge chamfer angle determined in previous work, the geometry was extended to a three-dimensional model that accounted for a 2 mm longitudinal pole extension at each end, introduced during fabrication to clamp the poles to the aluminum yoke. This extension altered the fringe-field distribution and degraded the integrated multipole content. A parametric sweep of the chamfer angle was therefore performed over the machinable range, and the angle minimizing the integrated harmonic content was selected.
The resulting geometry satisfies the field quality criteria for next-generation storage rings, with allowed multipole components below $5\times 10^{-5}$, forbidden components at the $10^{-5}$ level, and a field uniformity of 0.1% at $r_{ref} = 3 mm$. These results demonstrate the feasibility of a high-quality PMQ that provides a variable magnetic gradient without steady-state power consumption or cooling.
Funding Agency
This work was supported in part by the Basic Science Research Program through the National Research Foundation of Korea (NRF) through the Ministry of Education under Grant RS-2023-00247042
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