This week was a second week of scheduled maintenance and installation activities prior to the next attempt to push high power operation of the FEL and continuation of the test user experiments in User lab 1.

Several members of the group attended the ICFA 17th Advanced Beam Dynamics Workshop on Future Light Sources at Argonne national Lab this week. The workshop was concentrating on the next steps that DOE should take in the development of accelerator driven light sources.

The following is a list of FEL maintenance activities that were completed this week:

The Gun's photocathode was replaced, cesiated, and tested. The original quantum efficiency (QE) was 2.4 % in the center of the cathode. A short heat clean was done and high voltage processing is in progress. The QE will be checked again after HV processing to about 510 kV to determine if there is any effect on the cathode by the HV processing. We are presently at 416 kV this morning.

The new sapphire 3 micron mirrors for the Optical Cavity were installed and aligned.

Vacuum interlocks for the Optical Transport System were installed.

A pyroelectric detector was installed at 3F02, in the first 180° bending magnet. A vacuum leak developed and it was fixed the next morning.

The 30 ohm short in the 2G Dump was found and a temporary fix was installed to clear the short. A grounded LCW line was touching the dump.

The installation of the final shielding for the 1G Dump was completed and checked out by RadCon.

Numerous valves were installed so the diagnostic devices which require instrument air can be easily isolated from the beam line valves. This is to prevent any beam line from opening unexpectedly while nearby diagnostic devices are being removed from service.

The BPM's were checked again. The wires for 4F13 were connected properly and 4F01 & 4F12 were found to have high losses (10 dB) in their cables. The Gain will be adjusted, but new cables may be required at the next opportunity.

The software for an automated test of all BLM's was installed and tested. Also, all BLM's are now included in the MPS Master Reset.

Cables for the Optical Power head were installed between the vault and the upstairs rack. The rework effort of the Patch Panel system is in progress.

In order to improve the control and understanding of the electron beam orbit, magnets QG4F01, QG4F13, QB5F05, and QB5F06 were degaussed up to 10 amps, their 10 amp cards replaced with 1 amp cards, and generic 1 amp excitation curves installed in their software. Individual curves will be available by the end of April if this is not sufficiently accurate.