August 7, 2020 Meeting Minutes

Post-meeting notes

Joe presented rad monitor calibration, i.e. incident electron current to # counts measured by the radiation monitors. Calibration: ~0.2 nA current per count.
- Also showed plots of beam loss vs # counts near each steering coil.
Cristhian presented results from simulations showing the compensation time for secondary electrons due to SEY. The secondary electron production rate flattens over time to a steady rate due to the ion damage rate equilibrating over time.
- The beam potential does not change over time due to ions, probably because the number of ions trapped within the beam potential is significantly lower than the number of ions in the primary electron beam.
- Adjusting the maximum energy of the secondary electrons from SEY decreases the number of these electrons hitting the accelerator enclosure (beam pipe, gun chamber, apertures, etc.). Depending on the energy of SEY, the SEY beam characteristics are significantly different depending on the maximum energy of the SEY.
Josh will determine the equilibrium time of the ion damage rate - i.e. the time it takes for the last ion created by a single bunch to reach the photocathode