Conceptual design for proton accelerator with cyclotron auto-resonance

In recent years, an accelerator-based neutron source that replaces a nuclear reactor is being developed, and it is required to further increase the intensity of the accelerator. The automatic cyclotron resonance acceleration method is one of the acceleration methods that has succeeded in accelerating high-intensity electrons of 20 A with low energy up to about 2 MeV. The automatic cyclotron resonance acceleration method is a method in which an electric field rotating at the same angular velocity as a charged particle rotating in a magnetic field is generated and the charged particle is always accelerated in the same direction as the rotating direction. We apply the cyclotron auto-resonance acceleration to protons and aim to develop a proton accelerator that accelerates high-current protons to several tens MeV. Since the cyclotron resonance frequency is proportional to the magnetic flux density and inversely proportional to the mass of the particle, generation of a strong magnetic field is the key to realizing a cyclotron resonance accelerator for a proton with a mass of 2000 times that of an electron. A coil system using a high temperature superconducting wire and a resonant cavity for high frequency TE111 mode were designed by finite element electromagnetic field analysis using OPERA-3D to design an electromagnetic field with a static magnetic field of 8 T and circularly polarized light of 121 MHz. went. Furthermore, the behavior of the proton beam in this static magnetic field and electromagnetic field was calculated by OPAL, and the proton acceleration up to 30 MeV was confirmed. It was also shown that the charge contained in the proton bunch can be increased and the beam can be accelerated with a sufficiently small lateral spread even for a beam equivalent to 100 mA. In this presentation, we will present the calculation of magnetic field and resonant cavity, and the calculation result of proton orbit in the electromagnetic field. (author)