Tunable and temperature compensated permanent magnet assemblies for green particle accelerators

Abstract

Particle accelerators are developed worldwide for several societal, industrial, and scientific applications. With the advent of high-strength permanent magnets, the focus is shifting to building particle accelerators using permanent magnets for beam handling. This shift offers the distinct advantage of power efficiency and compactness, over electromagnets. However, such systems face inherent limitations related to temperature sensitivity and lack of tuneability. This paper explores and demonstrates methods for reducing temperature sensitivity and incorporating tuneability in permanent magnet-based systems. Accelerators employing a large number of permanent magnets are more energy efficient as they do not incur running expenditures and are therefore classified as green in this paper. Moreover, we believe that future particle accelerators will be able to leverage these advantages even more. A temperature-compensated magnet using a Nickel–Iron special alloy is designed using the measured temperature-dependent B–H curve of the material. The optimum thickness of the temperature-compensated shunt was determined and cross-verified by constructing a magnet and measuring it in a temperature-controlled environment. Additionally, this paper discusses the design of hybrid magnets integrating permanent magnets and electromagnetic coils highlighting their utility in temperature compensation and tunability. Furthermore, other methods for incorporating tunability and making a permanent magnet system more resilient to temperature changes are also briefly outlined.