Mainz 2022 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 14: Posters

AKBP 14.4: Poster

Thursday, March 31, 2022, 16:00–17:30, P

Improving the lifetime of GaAs-photo-cathodes with cryogenic components — •Tobias Eggert, Yuliya Fritzsche, and Joachim Enders — Institut für Kernphysik, TU Darmstadt, Germany

GaAs photocathodes provide a suitable source for polarized lectron beams. However, the operational lifetime is limited by a mandatory negative-electron-affinity (NEA) coating consisting of a cesium and oxygen. This layer gets corroded by oxygen over time and destroyed by ionized residual gas molecules hitting the surface. The latter is called ion back-bombardment (IBB) and is one of the main lifetime limiting factors. Improving the vacuum conditions around the cathodes surface is expected to reduce IBB and corrosion and therefore increase operational time. At the Institut für Kernphysik at TU Darmstadt a dedicated test stand is set up to develop a new kind of GaAs electron source, which uses cryocooling of a sub-volume to increase the vacuum condition around the cathode. In addition to the sub-volume, the cathode itself ets cooled to compensate for the temperature rise from high laser power.

This project is supported by DFG (GRK 2128) and BMBF (05H18RDRB1).