Photogun

100 keV photogun

  • 100-kV DC photogun with Cu photocathode, with 100-kV power supply, cable  and vacuum feedthrough, to be driven by a 200 nJ, 266 nm, 50 fs laser pulse
  • software for automated high-voltage training of  photogun
  • vacuum module with mirror mount for laser-incoupling to photocathode

 

 

 

 

The photogun is equipped with a 100-kV feedthrough designed for the high-voltage cable that comes with a Matsusada computer-controlled 100-kV power supply with breakdown detection. The photogun needs the usual training to withstand 100 kV. For this training it is recommended to apply an automated procedure: Simple software - available from AccTec B.V.- slowly turns up the high voltage until breakdown is detected. The breakdown signal then restarts the power supply at a lower voltage and resumes the training.

 

The photogun contains some materials (PEEK for the main insulator and teflon in the high voltage cable to the cathode) that are not compatible with ultrahigh vacuum. The Cu photocathode, however, operates with a long lifetime at an efficiency of 10-5 electron/photon in a vacuum of 10-6 mbar or better. For differential pumping between the photogun and a UHV-sample chamber, the laser incoupling unit provides pumping ports.

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