Kuriki, M. Guo, L. Negishi, K. Seimiya, Y. Urano, M. Yokota, A. JACoW Geneva, Switzerland 978-3-95450-182-3 10.18429/JACoW-IPAC2017-TUPAB050 English 1440-1442 TUPAB050 cathode laser vacuum electron experiment Contribution to a conference proceedings 2017 2017-05 http://dx.doi.org/10.18429/JACoW-IPAC2017-TUPAB050 http://jacow.org/ipac2017/papers/tupab050.pdf \rm CsK₂Sb is a high performance photo-cathode for accelerators requiring the high brightness electron beam. It can be driven by a green laser generated as SHG of a solid state laser. The quantum efficiency is as high as 10\%. In this article, the robustness of the cathode was studied experimentally. We found that 1/e lifetime of the cathode was inversely proportional to the vacuum pressure. The normalized temporal life was \rm (4.72± 0.08)× 10⁻⁵~Pa.hour for 532 nm laser. The lifetime regarding to the extracted charge density was also inversely proportional to the vacuum pressure. The normalized charge life was \rm (1.19± 0.03± 0.04)× 10⁻⁴ Pa.C/mm². The cathode is robust enough for a high brightness electron accelerator.