To: J. Albertine, D. Helms, W. Skinner
cc: Division (M7), FEL Coordination Group
From: F. Dylla
Subject: IRFEL Weekly Report, April 28-May 2, 1997
Date: May 2, 1997
Management
This week's highlights include successful start-up of the 350
kV test runs in the injector test stand and completion of the
wiggler acceptance tests at STI, Optronics. The ITS start-up
included the first test of the multislit emittance diagnostic
which performed at or above expectations. The wiggler has also
met or exceeded all technical specifications. After shipment
to Jefferson Lab later this month, the device will be inspected
and accepted by the project.
Five abstracts were prepared for presentations submitted at this
year's International FEL Conference which will be held in Beijing
in September. We have also been busy this week preparing for
the upcoming Particle Accelerator Conference which will be held
the week of May 12 in Vancouver.
The project monthly report for March was finalized and distributed
to DOE and the Navy Program Office.
In response to an action item generated at the April 14-15 review,
a preliminary plan for developing a back-up for the photocathode
drive laser was prepared and forwarded to the Navy Program Office.
We received from the Naval Postgraduate School their list of possible
coherent-synchrotron- radiation (CSR) experiments. We advised
them how to do a quick, cursory evaluation of the potential suitability
of each experiment, and we also provided some additional details
regarding plans for parametric studies of CSR with the IR Demo.
June 25-26 has been proposed as the dates for the next LPC workshop.
This notice was given in the April edition of "LPC Briefs"
that was distributed this week to the LPC contact list.
Injector Test Stand
Regarding the photocathode gun, we completed 80% of the checkout
of its beamline, with the rf kicker cavity being the only major
remaining system. We then fabricated a cathode and successfully
operated the gun with beam at 350 kV. However, the quantum efficiency
was only 1.25%. Nevertheless, the low quantum efficiency was
sufficient to support interesting and useful commissioning of
the multislit transverse-emittance diagnostic. We therefore operated
the beam at 250 keV for ~30 hours while making measurements with
the multislit. The tests have been very successful. As a side
note, the drive laser operated continuously for ~60 hours in support
of the multislit experiment. There were no problems.
Warm-up of the cryounit was completed as a prerequisite for installing
new ceramic warm windows. Two warm windows have been completed
and are being tested in the resonant-ring test fixture. They
are scheduled to complete qualification tests next week.
Some literature search was done to support planing for an advanced
drive laser. We developed a white paper for the laser upgrade
in response to an action item at last month's Navy review of our
FEL Program.
Accelerator Systems
Regarding the beam-transport system:
Parts for the first-article core for the optical-chicane dipoles
are being inspected prior to planned pinning next week at Everson
Electric. Magnet Enterprises International has wound all 16 coils
for these magnets and is shipping 5 today. We plan to do first-article
inspection of the core, and using the new assembly specification,
assemble a full magnet next week.
Tooling for the coils for the 180-degree, reverse-bend, and injection/extraction
dipoles is in fabrication. Process Equipment Company continued
manufacturing the cores for the 180-degree and reverse-bend dipoles.
Master Machine is starting fabrication of the cores for the injection/extraction
dipoles.
The new method of measuring rectangular Panofsky trim quadrupoles
worked, with the results at 80% of full field indicating 2% error
at the edges. Preliminary assessment indicates this is acceptable
for the beam-transport system, but final adjudication is pending.
The sextupole coils are in bidding, and the drawings of its
core will be signed today, 2 May 97.
Regarding corrector magnets, a television yoke manufacturer is
sending us a sample. We just received the papers written on a
simple design with good cut-off that was built at Lawrence Livermore
Lab. The mu-metal prototype core is complete, and its coils are
being wound.
The flat table for welding the X-chamber that connects the injection
line with the recirculation loop was received. Assembly started
on girders for the back leg.
Regarding the three quadrupoles for the recirculation-dump line,
we are marking up the prints of a QJ to double its length and
will soon go out for fabrication.
The drawings for the optical-chicane vacuum chambers were signed.
The design of the reverse- bend vacuum chambers continued at
Northrop Grumman.
Engineering designs of the scraper and insertable dumps is half
complete. A designer will flesh out the hardware early next week.
Regarding cryomodule fabrication:
Two cavity pairs (#s 2 and 4) are scheduled for rework next week as a result of failing their acceptance tests in the Vertical Test Assembly. One cavity pair requires complete reassembly which is scheduled for next week. The other requires replacement of a single component, and this is also scheduled for next week.
Two cryounits are in assembly with work progressing on schedule.
The copper shield for the third cryounit was slightly damaged
in shipping and was repaired this week.
Regarding electron-beam instrumentation and controls (I&C):
The balance of the printed circuit boards for the Machine Protection
System arrived from Argonne National Laboratory. They will be
assembled here.
6 beam-position monitors were delivered Monday, 30 Apr 97. Thirteen
more should arrive today, 2 May 97. They are being electrically
checked and turned over for assembly of the back-leg girders.
Problems with the pin welding were found on three of the electrodes.
We should be able to correct this in-house.
Magnet and cryogenic cable databases are complete.
FEL Systems
Wiggler
Certification scans for the wiggler at the specified field of 2.8 kG rms were completed this week as were scans at the commissioning field of 4 kG rms. Independent analysis of the data from the 2.8 kG scans confirmed that all specifications were met by large margins. The 14.6 mm gage blocks were installed, and measurements were made indicating that the field quality was not affected significantly. Some typical measurements for the 2.8 kG field are:
Specification Measurement
Phase jitter 5 degrees <1.4 degrees
Traj. wander 200 micron p-p <20 microns
Integ. x dipole <400 G-cm 29 G-cm
Integ. y dipole <400 G-cm 73 G-cm
The entrance and exit trajectory shift is less than 100 microns.
The wiggler will be shipped next Tuesday, 8 May 97, and should
be received by the 15 May 97 at the latest.
Our Machine Shop has had a hard time getting the required flatness
from their rolling setup and have switched to using a large hydrostatic
press to press the vacuum-chamber tubing into its final shape.
Inspection of the wiggler indicated some interferences between
bolts and the vacuum- chamber support. The drawings for the support
were modified to correct for the interference.
Optics
Hardware and tubing for the optical transport system (collimator,
mirror cans, and Brewster- window pick-off) began arriving this
week. Hardware for mounting the optical transport pipe upstairs
in the FEL Facility is also arriving. Design of the collimator
is nearing completion. The Pyrocam was tested and found to operate
normally.
Commissioning/Operations
Issues regarding field-uniformity requirements for the corrector
magnets and trim quadrupoles continued to be coordinated with
respect to existing commissioning plans. Considerations ranged
from using "poor" correctors, or even no correctors,
and moving magnet elements if necessary to adjust the beam (at
the expense of having "many knobs" on the transport
lattice), through pressing for high-quality correctors and trim
quads. One more possible corrector geometry was proposed, a double-coil
air-core configuration. If the prototype mu-metal core falls
short, this option may prove viable, and we are starting some
3D magnet-code calculations to explore its implications. Regarding
schedule, these magnets can be clamped on over the existing beam
pipe, so beam- transport installation can proceed without them.
Facility
It has been another very productive week for the FEL Facility.
We commissioned a tool crib in the linac area for storage of
sensitive equipment. We placed the pump skid for the dump and
began hookup to the water lines. A design concept for the crane
rail system in the injector area was proposed and accepted with
only minor changes. The stands for the cryounit and the buncher
and solenoid preceding it are installed. Only minor interferences
were found with existing equipment. Downstairs we had a minor
attack of flooding when a large downpour overpowered the sump
pump and water came down the truck ramp. No equipment damage
resulted, but some dirt was deposited in the injector pit. We
have since increased the size of the pump and are preparing to
install the asphalt dike system that was already on the drawings.
The gun high-voltage-power-supply tank was delivered to the tunnel,
and preparations are underway to install it and build up the electronics
in position.
Upstairs we hung the ceiling in the control room and optical lab.
Lights were installed and connected in the hung ceiling. Windows
were placed in the control room, but tile was not yet installed,
although the floor is prepared for it. Tile is being delivered
for all areas, so that should get underway shortly. Plumbing
hookups to the HVAC continued, as did plumbing connections for
the bathrooms which is now about 90% complete as far as internals
are concerned (no fixtures added yet, no drywall). The large
return duct was 75% complete in the utilities room. A second
coat of paint in the control room and a first coat in the RF gallery
were applied. Painting will continue through next week on the
ceiling in the RF gallery, plus lots of other touch up work on
I-beams, etc.. Exterior paneling is underway to complete the job
in the injector area and the storefront.
Electricians hung electrical transformers from the roof and mounted
switch boxes on the walls for those power feeds. Power conduits
are being installed in the ceiling area, 25% complete. We approved
overtime charges for the next two weeks for the electricians since
they are critical path for a number of activities and trade work.
Drywall taping and ceiling continues in the user labs. It is
about 50% complete. Dry wall went into the utility rooms and
the communications room in preparation for finishing the communication
conduits. We hope to have the cable pull by 15 May 97 and put
the building on the network by June 1. Preparations are underway
for hookup of low-contamination water (LCW) to the main machine
over the Memorial Day weekend to give the water a chance to circulate
through the purifiers for several days before it is needed to
run the nuclear-physics machine. Welding of LCW piping continued
downstairs.
We took over welding of the cryogenic sleeve from the contractor
in the belief that we could do the job better and faster. Sleeve
welding is complete and prepared for burial. The contractor prepared
to pour the slab for its base so it could be positioned and attached
to the lower-level feedthroughs. We did a general cleanup of
the second floor. The cryogenic line was declared finished and
leak free. When the sleeve is installed, the cryogenic lines
will be ready for welding to the line from the Central Helium
Liquifier.