MEMORANDUM
To: J. Cook, D. Helms, W. Skinner
cc: Division (M7), FEL Coordination Group
From: F. Dylla
Subject: IR Demo Project Weekly Report, November 17-21,
1997
Date: November 21, 1997
Management
The week's highlights include: (1) completion of SRF commissioning
of the linac cryomodule; the zero beam gradient for the module
was established to 47 MV vs. the 32 MV specification; (2) low
current electron beam was transported through the entire injector
line from the gun to the injector dump; and (3) the recirculation
dump line was put under vacuum.
On Thursday, Nov. 1, a contingent from NASA Langley Research Center
visited the laboratory to discuss NASA's interest in using the
IR Demo. One of the attendees, Dr. Wilson Lundy, manager of NASA's
Space Technologies Thrust Office, plans to release a request for
proposals to NASA-Langley during December. Dr. Lundy's office
will review proposals and offer funding for a selected number
of experiments slated to use the FEL User Lab that has been tentatively
reserved for NASA use.
On Wednesday, Nov. 21, a contingent from Hampton's Science and
Technology Corporation and the Army's Aberdeen Laboratory visited
the Laboratory to discuss possible use of the FEL for detecting
low concentrations of chemical and biological toxic agents.
On Friday, Nov. 22, F. Dylla presented a talk at a workshop on
"Materials Research Opportunities with FELs" hosted
by the Vanderbilt University FEL Center. Other presentations
at the workshop included contributions from several investigators
at Vanderbilt and NCSU who have submitted proposals to use the
IR Demo.
Installation Activities
Installation activities proceeded during first shift this week
and were focused on completing installation of hardware that would
allow beam to be transported through the linac cryomodule to the
recirculation dump. Accordingly, the last vacuum component (a
bellows connection to the downstream side of the cryomodule) was
installed and the dump line was put under vacuum. At the week's
end, dump instrumentation and shielding for initial low current
beam operations were being installed.
Alignment activities for the installed wiggler vacuum chamber and the up and downstream components are proceeding. This is the next section of the machine to be put under vacuum after alignment activities are complete. The wiggler viewer apertures were aligned with apertures on each optical table and the output brewster window installed and aligned. The opticaltables were enclosed in clean hoods. The optical mounts were prepared for installation next week.
The two long sections of the back leg return transport line were
given their final leak check and put under vacuum.
Three of the four DX arc dipole magnets were given their initial
alignment within installation.
The last two wedge dipole (DU) magnets were released from the
Magnet Test Stand for installation.
The first 180 degree arc dipole (DY) was installed in the east arc (minus its coil assembly) to allow vacuum chamber fit-up operations to proceed. The second 180 degree arc dipole (with a completed coil assembly) is installed in its magnetic measurement test stand which is now operational.
Commissioning Activities
Last Saturday we finished replacing the broken flow tube in the
drive laser and turned it on. That evening we resumed injector
commissioning. By week's end we had run tune-up beam into the
injector dump. The average current ranged up to roughly 1 µA
with bunch charges of order 1 pC. The measured electron-beam
momentum was 7.5 MeV/c, to within ±10%, with the two cryounit
cavities operating on crest. This value is lower than what was
expected based on the nominal accelerating gradients of the cavities
measured during the SRF commissioning process, and we need to
identify the source of the discrepancy. Electron-beam profiles
on the viewers are consistent with simulation (PARMELA) results.
SRF commissioning of the cryomodule was completed, resulting in a total available accelerating voltage of >47 MV. RF commissioning of the cryomodule should be completed this evening.