Third integer resonance extraction with presence of higher multipoles

Abstract

The slow resonant extraction of a beam in a storage ring is a very well-established technique. Several high-energy physics accelerator facilities around the world are currently using this technique for high-intensity beam operations. As the demand for beam power is constantly growing, extraction efficiency in many cases is becoming a limiting factor. In this report, we discuss a new effective approach to improving the slow extraction efficiency by using configurations of higher multipoles. We will describe this approach, determine optimal multipole configurations, and present the results of simulations to support the proposed recipe. We found that, with the use of higher multipole field content, the extraction efficiency can be improved, and, therefore, the level of prompt and residual radioactivity in the accelerator components and surrounding buildings can be reduced by as much as 40% or more. We also explored manipulating the higher-order effects produced in the pure sextupole configurations for the same purpose and demonstrated that similar results can be achieved by only rearranging the sextupole magnets in the lattice.