Field Emission and X-Ray Effect on Half-Wave Resonator (HWR) Superconducting Cavity Performance

Performance of superconducting cavities are investigated with field emission effect and x-ray detection. Conducting particles and surface curvature can cause field emission from the surface of the superconducting Nb cavity. The field emission makes the local temperature increase, the surface resistance increase, and then the quality factor decrease. Vertical test is performed for half-wave resonator (HWR) cavities. The vertical test facilities are introduced and the quality factors are measured for the half-wave resonator (HWR) cavities. The quality factors of the cavities decrease as the x-ray are increased. The surface resistance and x-ray generation of the cavity can be fitted well with the field emission theory. The quality factors for the half-wave resonator (HWR) cavities decrease linearly with the field enhancement factor for x-ray generation.