Beam extraction by the laser charge exchange method using the 3-MeV LINAC in J-PARC

The Accelerator-driven System (ADS) is one of the candidates for transmuting long-lived nuclides, such as minor actinide (MA), produced by nuclear reactors. For the efficient transmutation of MA, a precise prediction of the neutronics of the ADS is required. To obtain neutronics data for the ADS, the Japan Proton Accelerator Research Complex (J-PARC) has a plan to build the Transmutation Physics Experimental Facility (TEF-P), in which a 400-MeV positive proton (H⁺) beam will be delivered from the J-PARC linac. Because the TEF-P requires a stable and low background proton beam with a power of less than 10 W, a stable and meticulous beam extraction method is required to extract the low power proton beam from the high power negative hydrogen (H⁻) beam of 250 kW. To fulfill this requirement, a new type of Laser Charge Exchange (LCE) device was developed. A feature of this LCE device is the elimination of the background protons that are not extracted by the LCE technique. To demonstrate the charge exchange of H⁻, an LCE experiment was conducted using a linac with an energy of 3 MeV in J-PARC. As a result of the experiment, a charge-exchanged H⁺ beam with a power of 7.99 ± 0.22 W equivalent was obtained under the J-PARC linac beam condition, and this value nearly satisfied the power requirement of the proton beam for the TEF-P. (author)