Experiences with permanent magnets at the Fermilab recycler ring

Abstract

In order to achieve higher luminosities in Run II a separate anti proton storage ring was built in the Main Injector tunnel. To reduce both construction and operations costs permanent magnets were used. This paper discusses the design criterion and specifications, including temperature dependence, longitudinal uniformity, and adjusting of the higher harmonics of the magnets. The design tolerances for a storage ring are more stringent than for a single pass beam line. The difference between the measured and ideal central field for each magnet was held to better than one part in 10 3 . The temperature stability for all magnets was set to better than 1 part in 10 4 per degree Celsius. Higher order harmonics relative to the central field were set to less than 1 part in 10 4 . This was done for all 484 permanent magnet that were built.

Accelerator Technology and Beam Physics of Future Colliders

“…For lower fields, up to of order 1 T, permanent magnets are most energy efficient. An example is the Fermilab Recycler Ring [50], which was built almost entirely from permanent magnets. Even adjustable permanent magnets have been designed and built for applications at light sources, colliders, and plasma accelerators [51].…”

Measuring field multipoles in accelerator magnets with small-apertures by an oscillating wire moved on a circular trajectory

“…In particle accelerators, the beam stability is affected by magnetic field inhomogeneity in the bending and focusing magnets. Therefore, a high field quality [1]- [4], characterized by the harmonic coefficients of the transverse field expansion, is required. High-accuracy measurements of these coefficients, usually denoted as field multipoles [5], are prevalently based on rotating search coils [6]: a wire loop, of area A and N turns, is rotated at the angular frequency ω in the magnet field.…”

The Legacy of the Tevatron in the Area of Accelerator Science

“…Cross section of the Tevatron superconducting dipole magnet.3.1.2 Permanent MagnetsBecause of the low ratio of beam momentum to circumference, the Recycler was uniquely suited for utilization of permanent magnets(33,34). The advantage of permanent magnets was the low construction and operating coststhe Recycler may well be the lowest cost per GeV accelerator/storage ring ever constructed.The Recycler lattice optics replicate those of the Main Injector.…”