In-vacuum thin eddy-current septum magnet for innovative off-axis beam injection in next-generation light source

Beam injection is one of the most crucial issues for next-generation light sources such as diffraction-limited storage rings. We propose a novel transparent off-axis beam injection scheme for low-emittance storage rings of future light sources. The scheme aims to achieve efficient beam injection into a narrow dynamic aperture with small injection amplitude, while minimizing perturbation to the stored beam with transparent beam injection. An in-vacuum thin eddy-current septum magnet is one of the key components of the scheme to achieve the small injection amplitude. A prototype of the magnet with an accommodating ultrahigh vacuum (UHV) chamber was designed and fabricated. Magnet performance of the prototype demonstrated that an injection amplitude as small as 3 mm is feasible, fulfilling the tight constraint of injection amplitude in off-axis beam injection for next-generation light sources. The prototype achieved a UHV pressure of better than <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>1</a:mn><a:mo>×</a:mo><a:msup><a:mn>10</a:mn><a:mrow><a:mo>−</a:mo><a:mn>7</a:mn></a:mrow></a:msup><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>Pa</a:mi></a:mrow></a:math>, ensuring the vacuum performance required for stable operation in storage rings.