An independent continuous wave LINAC (HElmholtz LInear ACcelerator HELIAC) in combination with the upgraded GSI High Charge State Injector can best meet the requirements of these experimental programs.
The heavy ions are accelerated by means of so-called crossbar H-mode (CH) cavities. The first CH structure (CH0) was already tested in summer 2017 and then successfully used for heavy ion acceleration last year. The next step is the development of the next two CH structures (CH1 and CH2) in order to put a fully equipped HELIAC cryomodule (CM1) into operation and also use it for ion acceleration. In summer 2018, CH1 was already successfully tested for its maximum performance by our collaboration partners at the Institute of Applied Physics at the Goethe University in Frankfurt. Overall, the cavity achieved a maximum acceleration gradient of EA ≈ 9.2 MV/m, which is significantly above the HELIAC requirements of EA = 5.5 MV/m. In the meantime, CH1 has been fitted with an additional tank jacket by the manufacturer. Initial performance tests on CH2 showed a cold leak after cooling to cryogenic temperatures - recently the necessary repair work has been completed.
Both CH cavities were delivered in November. CH1 is now installed in the horizontal test cryostat and is currently tested under cryogenic conditions in the HIM test bunker. CH2 will undergo another performance test in the vertical cryostat in Frankfurt at the beginning of 2020. - Results of the Rf tests are expected shortly.