The KONUS IH-DTL proposal for the GSI UNILAC poststripper linac replacement

H Hähnel,U Ratzinger,R. Tiede

doi:10.1088/1742-6596/874/1/012047

H Hähnel, U Ratzinger + Show 1 more

Open Access

https://doi.org/10.1088/1742-6596/874/1/012047

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Abstract

Motivated by the necessary replacement of the GSI UNILAC poststripper linac, a compact and efficient linac design based on IH-type cavities has been developed. Using KONUS beam dynamics, it was possible to design a linac consisting of only five cavities that can be operated by the existing UNILAC RF amplifier structure. The transversal focusing scheme is based on magnetic quadrupole triplet lenses. The optimized design provides full transmission and low emittance growth for the design current of 15 emA U28+, accelerating the beam from 1.4 MeV/u to 11.4 MeV/u. Extensive error studies were performed to define tolerances and verify the stability of the design with respect to misalignment and injection parameters. The design provides a compact and cost effective alternative to a new Alvarez linac. With a total length of just 22.8 meters it will leave room for future energy upgrades in the UNILAC tunnel.

Highlights

Published under licence by IOP Publishing Ltd of five IH-DTL cavities and seven quadrupole triplet lenses [6, 7], as shown in figure 2. It can be operated by the existing UNILAC RF amplifier structure well within power limits [8, 9]
The first cavity is designed with two internal lenses, a technology that has proven reliable in several linacs built in the last decades (e.g. HSI [10] and HLI [11] at GSI UNILAC, the HIT Heidelberg [12], NICA at JINR Dubna [13])
To achieve low longitudinal emittance growth, the KONUS lattice was optimized for an average beam current of 15 mA U28+

Summary

Introduction

To achieve low longitudinal emittance growth, the KONUS lattice was optimized for an average beam current of 15 mA U28+. Error compensation using corrective steering elements within the linac was investigated, showing significant improvement of the linac performance. The investigated errors include the displacement of the quadrupole magnets and cavities, a rotation of the magnets, field errors of the RF cavities and errors of the injected beam parameters. For the magnetic quadrupole triplet lenses, the displacement and rotation of the individual singlets and the triplets as a whole were investigated, as well as gradient errors.

Results

Conclusion