AVS 65th International Symposium & Exhibition
    Vacuum Technology Division Tuesday Sessions
       Session VT-TuM

Paper VT-TuM11
Thin film Heterostructures for Superconducting Photocathode Applications

Tuesday, October 23, 2018, 11:20 am, Room 203B

Session: Large Vacuum Systems and Accelerator Vacuum Technology
Presenter: Mark Warren, Illinois Institute of Technology
Correspondent: Click to Email
In the application of high pulse rate (100 MHz) CW light sources, superconducting RF guns serve as ideal photoinjectors as they dissipate significantly less power than normal metal Cu. An integral component of a photoinjector, the photocathode, must produce an electron beam with stringent requirements on emittance, temporal response, and quantum efficiency (QE). The photoinjector wall material is most commonly Nb which itself has a low QE (10-6). So, it is proposed that Nb photocathodes be coated with thin films of Mg which have a much higher QE (0.1% with laser cleaning) and can be induced into the superconducting state via the proximity effect. Results on the fabrication and testing of Nb/Mg bilayers including the resiliency of thin films in high RF fields (up to 60 MV/m) will be presented. In addition, the study of semiconducting overlayers is presented including promising QE values in ultra-thin layers of Cs2Te on Nb.