To: J. Cook, D. Helms, W. Skinner

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IR Demo Project Weekly Report, February 2-6, 1998

Date: February 6, 1998

Management

Highlights for the week included the successful cool-down of the linac as the Central Helium Liquifier (CHL) came back on line; a recheck of the injector cryounit and linac cryomodule performance after the temperature cycle, and restart of gun/injector operations with beam.

On Feb. 5th, F. Dylla and C. Leemann met with DOE-BES officials with colleagues from BNL, SLAC and UCLA to discuss near term R&D which should be done in preparation for a potential FEL-based 4th generation light source. The group concluded that a proposed demonstration at BNL of a self-amplified FEL in the visible wavelength range and the planned CSR measurements using the Jefferson Lab FEL are high priority activities.

A draft agenda for the Navy FEL program meeting on Feb. 17-18th was distributed to the Navy and DOE Program Offices on Friday.

Installation Activities

The BPM's to the straight ahead dump, 2G, were installed and connected this week.

Two 8 kW klystrons were installed and operated satisfactorily in the FEL cryomodule.

The raster magnet for the 2G dump was installed and wired. Several vacuum leaks in this dump line were fixed.

The MPS system installation is in progress and is scheduled to be complete next week.

The mirror mounts for the optical cavity were removed for reworking because of a warping problem caused by the present o-ring configuration (which will be changed). A leaking cooling water fitting was replaced on the drive laser.

Installation was completed to provide LCW cooling for the trim magnet resistors.

SRF and RF completed their checkouts of the combined RF system.

Commissioning Activities

Beam commissioning activities were resumed on Thursday after cooldown of the linac and RF/SRF check-out. Tune-up beam was accelerated through the cryounit and viewed as a small round spot. Thus, the mis-positioned valve discovered at the start of the January shut-down appears to have resolved the beam shape issue discovered during the December run. The multi-slit diagnostic produced clear distinct stripes. Bob Legg reported that the gun stalk was drooping causing an alignment problem with the first solenoid and the cathode wafer may be cocked causing field emission and arcing at 348 kV. These problems will be addressed over the weekend. By working in parallel, additional time for SRF and RF tests is thus available. A revised schedule was made reflecting the tasks and times available for testing.

The injector cryounit can be operated at 11 and 9 MV/m after the warm windows were changed and testing by SRF. B. Yunn agreed these were the values to use according to his simulations. The cryomodule cavity 4 runs only to 7 MV/m due to window temperature, but it is still being worked. The other cavities experienced no changes due to the isolation valve change-out and temperature cycling in December.

R. Walker noted the FEL enclosure is now a Radiologically Controlled Area, with access covered by a General RWP. All persons who enter the FEL vault need to read and sign the RWP in the FEL control room.