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.