High-gradient test results on a quadrant-type x-band single-cell structure

A common normal-conducting high-gradient accelerating structure of particle accelerators is the "disk type", which has dozens of machined, stacked, and bonded disks. In the disk type, surface currents associated with a magnetic field of an accelerating mode flow across disk-to-disk junctions. Another structure is the "quadrant type", which is orthogonal to the above type. In the quadrant type, bonding planes are parallel to a beam axis, and therefore, this type has the remarkable feature that no such surface current flows across any junction. We have proposed, designed, fabricated, and tested an improved quadrant-type X-band (11.4 GHz) single-cell structure, and then demonstrated its efficacy and the potential for this structure to be successful for gradients of 100 MV/m or higher at sufficiently low breakdown rates.