GTS meeting 5 17 16
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- Generated beam at 275kV[1]
- No real limitation on voltage, we stopped there b/c we observed 'beam' on the viewer. Fearing it would be Field Emission from the multi-alkali photocathode, we stopped at this voltage.
- Later on we realized it was real photoemission beam from ambient light being picked up through the gun laser input viewport!
- This indicated right away that the multi-alkali photocathode has good QE, contrary to what we estimated in the cathode prep chamber, see discussion below
- We ran with the least possible amount of laser power
- We need to fix the following:
- Two viewer cameras (old, removed from FEL) have radiation damage, hard to see the image
- Make a shade to prevent ambient room light reaching the photocathode
- Carlos to coordinate with RadCon for Rad measurements during beam steering to get permission to run at full current.
- What we must do, it would be essential, and really cool!
- Carlos to contact software to get Keithely Dump current in EPICS
- Shukui and Carlos to work with software for re-commissioning cathode QE scanner. This will have to be done with the gun biased at ~1kV
- Measuring QE in the cathode prep chamber with the slope of I vs Laser Power to make sure we stay away from charge saturation
- Let's discuss beam measurements plans!