LINAC2026 - 33rd Linear Accelerator Conference

Introduction of co-deposition method for improvement of quantum efficiency and lifetime of Cs-Te photocathodes in KU-FEL

Not scheduled

2h

Daejeon Convention Center

Poster Presentation MC1.A02 Electron and ion sources, guns, photo injectors, charge breeders Poster Session

Speaker

Mr Yutaro Kubo (Kyoto University)

Description

Cs-Te photocathodes are widely used in photoinjectors for free electron lasers owing to their high quantum efficiency (QE). At KU-FEL, an infrared oscillator-type FEL in Kyoto University, a 1.6-cell RF gun with CsBr-coated Cs-Te photocathode has been developed for high-bunch-charge (~1 nC) multi-bunch operation. However, the QE and lifetime of the cathode in our RF gun are insufficient for practical use. In 2024, CERN group reported that the QE of Cs-Te photocathode made by co-deposition has significantly higher than that made by sequential deposition*. Therefore, we are planning to introduce the co-deposition method to our system to increase the QE and lifetime of the cathode. Right now, a co-deposition source compatible with our UHV chamber was designed and fabricated. Co-deposition experiments are planned in May 2026. Results with co-deposition and sequential deposition of Cs-Te photocathodes in our system will be reported in the conference.

Footnotes

H. Ono et al., Jpn. J. Appl. Phys. 58, 066005 (2019).
*M. Martinez-Calderon et al., Phys. Rev. Accel. Beams 27, 023401 (2024).

Funding Agency

MEXT Q-LEAP (JPMXS0118070271)