Development of sodium potassium antimonide photocathodes for use of coherent electron cooling

The Coherent Electron Cooling (CeC) technique is a breakthrough in accelerator science, enhancing ion beam brightness in facilities like the Electron-Ion Collider (EIC). The success of CeC relies on high-performance photocathodes (PCs) for photoinjectors, where ideal PCs exhibit high QE, low emittance, long lifetimes, and minimal dark current. Alkali antimonide PCs meet these requirements. Among these, Na-K-Sb shows enhanced robustness, particularly under high-temperature conditions from high-power laser illumination, which generates high current electron beams. It also demonstrates improved vacuum stability and long-term QE consistency compared to other alkali antimonides like K2CsSb and Cs3Sb. These attributes make Na-K-Sb an effective choice for applications requiring both thermal and vacuum stability. This work presents the growth of Na-K-Sb PCs using the CeC cathode deposition system, alongside detailed QE measurements and spatially resolved QE maps. These findings highlight the potential of Na-K-Sb PCs to advance CeC performance significantly and foster the development of high current, high-brightness electron sources for broader applications