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MOPA18 |
A Racetrack-Shape Fixed Field Induction Accelerator for Giant Cluster Ions | |
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Funding: Grants-In-Aid for Scientific Research （B)（KAKENHI No. 15H03589) A novel scheme for a racetrack-shape fixed field induction accelerator (RAFFIA) capable of accelerating extremely heavy cluster ions (giant cluster ions) * is described. The key feature of this scheme is rapid induction acceleration by localized induction cells. Triggering the induction voltages provided by the signals from the circulating bunch allows repeated acceleration of extremely heavy cluster ions. Under the hypothesis that the RAFFIA is an induction synchrotron ** with an adiabatically varying circumference, the given RAFFIA example is capable of realizing the integrated acceleration voltage of 50 MV per acceleration cycle for C-60 (A=720 and Q=7). Using 90° bending magnets with a reversed field strip and field gradient is crucial for assuring orbit stability in the RAFFIA. Interesting beam physics such as resonance crossing during an acceleration cycle is discussed, including the structural stability of the cluster ion itself in the bending fields. * K.Takayama, T.Adachi, M.Wake, and K.Okamura, Phys. Rev. ST-AB 18, 050101(2015). ** K.Takayama and R.J. Briggs, Chapter 11 and 12 in Induction Synchrotron (Springer, Heidelberg, 2011). |
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WEPB19 |
Laser Ablation Ion Source for Highly Charge-State Ion Beams | |
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Acceleration experiments of gaseous heavy ions delivered from the ECR ion source are in progress in the KEK Digital Accelerator(KEK-DA)*. KEK Laser ablation ion source (KEK-LAIS) has been developed to generate highly ionized metal ions and fully ionized carbon ions since 2012**. Basic parameters such as a charge-state spectrum, momentum spectrum, spatial distribution of the plasma current, extracted ion beam current, and emittance have been obtained. Since diffusion of a laser ablated plasma is known to be controlled by magnetic guiding fields***, these parameters are measured as a function of solenoid guide fields and its length. Meanwhile, 10Hz continuous ablation plasma experiment, which is a crucial trial for accelerator applications, will be carried out with a newly developed moving target. The stability in accelerator beam parameters such as the pulse width and intensity is confirmed. At the conference, the extraction of heavy ion beams from the LAIS and post acceleration will be also discussed, including beam optics through the low energy beam transport line to the KEK-DA.
* K. Takayama et al., Phys. Rev. ST-AB 17 (2014) 010101. ** N.Munemoto et al., Rev. Sci. Inst. 85, 02B922 (2014). *** M. Okamura et al., Rev. Sci. Inst. 81, 02A510 (2010). |
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