Superconducting CH-cavity heavy ion beam testing at GSI

W Barth,A Schnase,M Heilmann,T Kurzeder,M Miski-Oglu,M Busch,F Dziuba,H Podlech,V Gettmann,A Rubin,K Aulenbacher,M Basten,M Schwarz,S Yaramyshev

doi:10.1088/1742-6596/1067/5/052007

Abstract

Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI High Charge State Injector (HLI). The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain of 0.5 MeV/u was achieved with heavy ion beams even above the design mass to charge ratio at maximum available beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and -phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications.

Highlights

R&D and prototyping [1,2] in preparation of the proposed HElmholtz LInear ACcelerator (HELIAC) is assigned to a collaboration of GSI, Helmholtz Institute Mainz (HIM) and Goethe University Frankfurt (GUF)
The support frame, as well as the accelerator components, are suspended each by eight tie rods in a cross-like configuration balancing the mechanical stress during the cool down and warm up
For further matching to another Crossbar H-mode structures (CH)-cavity, the adjustment of the beam energy setting by changing the RF-amplitude is more favourable - compared to changing the RF-phase as no significant bunch shape change could be observed

Summary

Introduction

R&D and prototyping (demonstrator project) [1,2] in preparation of the proposed HElmholtz LInear ACcelerator (HELIAC) is assigned to a collaboration of GSI, HIM and GUF. Promising power and beam tests with the 15-gap CH0 showed successfully, that higher accelerating gradients can be achieved, leading to a more efficient design with four cryo modules (CM1-CM4). At June 2017, after successful RF-testing of the sc RFcavity in 2016, set up of the matching line to the demonstrator and a short commissioning and ramp up time of some days, the CH0-cavity first time accelerated heavy ion beams (Ar11+) with full transmission up to the design beam energy of 1.866 MeV/u ( Wkin = 0.5 MeV/u) [21].

Results

Conclusion