Development of a novel tunable gradient permanent quadrupole magnet

Addressing the demands for compactness and tunability in magnet systems for fourth-generation light sources, this paper presents the design and development of a novel tunable permanent quadrupole magnet (PQM) prototype. The prototype achieves a maximum field gradient of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>65</a:mn> <a:mrow> <a:mrow> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi mathvariant="normal">T</a:mi> </a:mrow> <a:mo>/</a:mo> <a:mi mathvariant="normal">m</a:mi> </a:mrow> </a:math> and demonstrates a continuous tuning range of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mn>39</e:mn> <e:mrow> <e:mrow> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:mi mathvariant="normal">T</e:mi> </e:mrow> <e:mo>/</e:mo> <e:mi mathvariant="normal">m</e:mi> </e:mrow> </e:math> . Within the effective aperture, normalized multipole field components are maintained below <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mn>5</i:mn> <i:mo>×</i:mo> <i:msup> <i:mn>10</i:mn> <i:mrow> <i:mo>−</i:mo> <i:mn>4</i:mn> </i:mrow> </i:msup> </i:math> . Experimental validation confirms that the prototype meets the engineering design requirements for the Hefei Advanced Light Facility. Compared to conventional electromagnetic quadrupoles, this PQM features a compact structure, with negligible power consumption and high magnetic field quality, representing a promising technology for advanced synchrotron radiation light sources and free-electron lasers.