Speaker
Description
At the J-PARC 3 GeV Rapid Cycling Synchrotron (RCS), a 400 MeV negative hydrogen (H-) beam from the linac is converted to proton (H+) using a charge-exchange foil and then accelerated to 3 GeV. As the beam power has increased toward the design value of 1 MW, foil de-formation and breakage of the SiC support fibers caused by beam irradiation have become major issues, leading to beam dump temperature rises that obstruct stable opera-tion. To improve the reliability of the charge-exchange foil under high power conditions, a stepwise develop-ment has been carried out. First, a pure carbon foil was developed to suppress irradiation induced deformation. Beam operation showed reduced deformation compared with previously used hybrid boron-mixed carbon (HBC) foil and graphene thin film (GTF), and beam dump tem-perature rises were not observed. Next, the arc deposition parameters were optimized by increasing the anode di-ameter, resulting in further reduction of deformation in beam operation. Finally, carbon nanotube (CNT) wires were adopted as support fibers instead of SiC fibers. The CNT-supported foil was successfully operated up to 940 kW-equivalent beam power for over 1 month without support failure and beam dump temperature rises. These results demonstrate improved durability of the charge-exchange foil and support stable RCS operation toward 1 MW beam power.
| Paper status | Resubmitted proceeding files received and assigned to an editor. Accepted by Submitter. |
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