Low-power test of bridge coupler in disk-and-washer structure for muon acceleration

A muon linear accelerator is under development at J-PARC for precise measurement of the muon anomalous magnetic moment (g-2) and electric dipole moment (EDM). A disk-and-washer (DAW) structure is employed to accelerate muons from 30% of the speed of light (kinetic energy = 4 MeV) to 70% (40 MeV) at 1296 MHz. The muon DAW consists of tanks accelerating the muons and bridge couplers that couple the tanks and focus the beam using an internal quadrupole doublet. A bridge-coupler prototype is currently being fabricated and will be tested. This paper presents the design and performance evaluation of the bridge coupler prototype.