Results from validation experiment for three-dimensional spiral beam injection scheme

A three-dimensional spiral beam injection scheme\* has been developed since 2014. This scheme is for accumulating a charged particle beam with relativistic energy in a sub-meter storage ring to realize for the J-PARC Muon g-2/EDM experiment (E34). Prior to the E34 experiment, we conducted a demonstration experiment utilizing 80 keV pulsed electron beam generated by an electron gun\**. The beam passed through a transport line of three rotating quadrupoles and was accumulated in an 80gauss solenoid magnet at the center fiducial volume with a diameter of storage orbit only 24cm. Now we have successfully accomplished (1) a strongly X-Y coupled beam phase space to inject into the axisymmetric solenoid magnetic field, (2) a weak focusing magnetic field potential within the storage region at the center of the solenoid magnet, (3) a pulsed magnetic field kick to guide the beam trajectory into the storage region, and (4) beam diagnosis in the storage area. In this presentation, we will report the experimental results of successful storage in an ultra-compact ring, and improvements for the actual storage ring for E34 based on this knowledge gained from 10 years of demonstration experiments.