Yin, Z.Y. Hartung, W. Kim, S.H. Konomi, T. Xu, T. JACoW Publishing Geneva, Switzerland 2673-5504 978-3-95450-234-9 10.18429/JACoW-SRF2023-WEPWB113 English 859-862 cathode simulation electron SRF experiment Contribution to a conference proceedings 2023 2023-09 https://doi.org/10.18429/JACoW-SRF2023-WEPWB113 https://jacow.org/srf2023/papers/wepwb113.pdf The high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE) will increase the photon energy and brightness. A low-emittance injector (LEI) was proposed to increase the photon flux for high X-ray energies. FRIB, HZDR, Argonne, and SLAC are developing a 185.7 MHz superconducting radio-frequency photo-injector (SRF-PI) cryomodule for the LEI. The photo-cathode system requirements are challenging, as cathodes must be maintained at the desired temperature, precisely aligned, and operated without multipacting (MP); to avoid field emission, cathode exchange must be particulate-free. A support stalk has been designed to hold the cathode in position under these requirements. A DC bias is used to inhibit MP. We simulated MP for various surface conditions and bias levels. An RF/DC test was developed to evaluate the cathode stalk performance as a subsystem and to identify and correct issues before assembly into the full cryomodule. The RF/DC test makes use of a resonant coaxial line to generate an RF magnetic field similar to that of the cathode-in-SRF-PI-cavity case. High-power test results will be presented and compared to the MP simulations.