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In the future, a new superconducting (SC) continuous wave (CW) high intensity heavy ion HElmholtz LInear ACcelerator (HELIAC) should provide ion beams with maximum beam energy above the Coulomb barrier for the Super Heavy Element program at GSI (Gesellschaft für Schwerionenforschung, in Engl.: Association for Heavy Ion Research). The HELIAC consists of a SC main accelerator supplied by a normal conducting injector, which comprises an electron cyclotron resonance ion source, a radio-frequency quadrupole, and two separate interdigital H-mode drift-tube linear accelerator cavities, based on an Alternating Phase Focusing (APF) scheme. Together, both cavities will accelerate ions from 300 to 1400 keV/u with only one external quadrupole triplet for transverse focusing in between. Due to the demanding requirements of the APF concept on the voltage distribution along the beam axis on the one hand and the CW operation on the other hand, the optimization of each cavity concerning RF, mechanical, and thermal properties is crucial for the successful operation of the HELIAC injector. [ABSTRACT FROM AUTHOR]

The new heavy ion superconducting continuous wave HElmholtz LInear ACcelerator (HELIAC) is under construction at GSI. A normal conducting injector, comprising an ECR ion source, an RFQ and a DTL, is recently in development. The new Interdigital H-mode DTL, presented in this paper, accelerates the heavy ion beam from 300 to 1400 keV/u, applying an Alternating Phase Focusing (APF) beam dynamics scheme. This APF section, consisting of two separately controlled tanks, has to provide for stable routine operation with assistance of dedicated beam diagnostics devices in the Intertank section. The installed quadrupole lenses and beam steerers installed there ensure full transmission in a wide range of input beam parameters. [Display omitted] • Alternating phase focusing has been applied for low emittance growth heavy ion beam transport. • Realistic 6D coupling for all phase planes has been considered. • Two radio frequency resonators have been designed to provide for continuous wave operation. • For beam dynamics design, a parallel global optimization search strategy has been adopted. [ABSTRACT FROM AUTHOR]

The standalone superconducting continuous wave heavy ion linac HELIAC (HElmholtz LInear ACcelerator) is a common project of GSI Helmholtz Centre for Heavy Ion Research and Helmholtz Institute Mainz (HIM) under key support of Goethe University Frankfurt (IAP) and in collaboration with National Research Nuclear University MEPhI and NRC "Kurchatov Institute" ITEP. In 2017 the first superconducting section of the linac has been successfully commissioned and extensively tested with beam at GSI. The measurements sufficiently present the capability of 216.816 MHz multi-gap Crossbar H-mode (CH) DTL-structures. An acceleration of heavy ions up to the design beam energy and beyond has been reached with the setup. 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. Recently the HELIAC beam dynamics concept foresees twelve superconducting CH-DTL cavities, assembled in four cryomodules. Each module is equipped with three accelerating CH structures, two superconducting solenoids for transverse beam focusing and a Spoke-type buncher for longitudinal beam matching. The linac is used to accelerate ions with a mass-to-charge ratio up to A ∕ z = 6 from the input energy of 1.4 MeV/u up to the smoothly variable output energy between 3.5 MeV/u and 7.3 MeV/u. The manuscript presents the reference beam dynamics layout of the entire HELIAC facility. [ABSTRACT FROM AUTHOR]