|THPGW029||Crucial Transverse Beam Dynamics of the Racetrack-shape Fixed Field Induction Accelerator for Giant Cluster Ions||3643|
A racetrack-shape fixed field induction accelerator (RAFFIA) for high energy giant cluster ion acceleration was proposed in 2015*. The RAFFIA employs 4 bending magnets with gradient in the main pole face and reverse field strip at its front side which generate strong focusing in both planes. Beam dynamics properties of the RAFFIA of 140 MeV for C-60 have been evaluated by linear optics. The result has been confirmed with a help of 3D macro-particle computer simulation**. It is identified that the issue of COD generated from field non-uniformity associated with a finite size of the bending magnet is inherent. The programmed COD correction by steering magnets are discussed as well as the importance of uniformity in the magnet field profile. So far it has been unknown what beam current is acceptable in the RAFFIA. In order to estimate space-charge effects in the RAFFIA under design, the 2D core (σ) evolution equation has been derived from the envelope equation perturbed by space-charge fields. Resonant structures and chaotic motion in the phase space of (σ,σ’) have been clarified as a function of beam current. Those results were justified by macro-particle tracking based on a renormalized transfer matrix approach***. As a result, it turns out that the 8+ C-60 beam of 200 uA is acceptable.
* K.Takayama, et. al, Phys. Rev. ST Accel. Beams 18, 050101 (2015).
** Taufik, et. al, sub. to Phys. Rev. AB (2018).
*** Taufik, K.Takayama, and T. Adachi, sub. Phys. Rev. AB (2019).
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW029|
|About •||paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019|
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