MEMORANDUM
To: J. Albertine, D. Helms, W. Skinner
cc: Division (M7), FEL Coordination Group
From: F. Dylla
Subject: IRFEL Weekly Report, August 4-8, 1997
Date: August 8, 1997
Management
Highlights for the week included testing of the new HV supply
for the gun in the FEL facility to 200kV in air and the wiggler
was reinstalled and surveyed into the correct final position.
This week the FEL Project received $3.7M of Navy funding for the
period Aug. 1997 to Sept. 1998 for the tasks of preparing the
IR Demo for commissioning, commissioning the IR FEL, and initial
design and procurement activities for the IR Upgrade. Receipt
of this funding follows the signature last week of the second
Navy-DOE Memorandum of Agreement for the IR Demo Project.
Review and revision of the pre-proposals that were submitted last
month for initial use of the IR FEL continued. Discussion was
initiated with NREL on a possible collaboration on the use of
the IR FEL for applications to photovoltaic materials.
On Friday, F. Dylla visited DuPont Experimental Station for an
update on DuPont's proposals and plans for the polymer lab in
the FEL User Facility.
Discussions are on-going with both DuPont and Armco with regard
to their comments on the initial draft of a User Facility Agreement
for the FEL user labs that would incorporate their equipment provisions
for the polymer and metals labs, respectively.
Jefferson Lab was invited to co-sponsor a Workshop on Fourth Generation
Light Sources that will be held at the Advanced Photon Source
(Argonne, IL) on Oct. 28-30. The workshop will focus on the FEL
technology and applications for deep UV and X-ray FELs.
The Navy Program Office has tentatively identified Oct. 1-3 as
the timeframe for a site visit and review of the IR Demo Project.
Work intensified on writing papers and preparing presentations
for this month's Free-Electron Laser Conference. Jefferson Lab
has five scheduled presentations there concerning the IR Demo.
Accelerator Systems
Regarding the beam-transport system:
Installation of the injection line in the FEL Facility continues
to progress. The mismatch in the height of the injection-line
dump reported last week was completely fixed; the dump is now
bolted to the beamline leading to it.
We characterized with the Hall probe six of the seven optical-chicane
dipole magnets that came in last week. Their field profiles generally
look reasonable. Results from the core-field measurements show
a deviation from the population average by ± 0.2% as compared
to our desire to achieve ± 0.1%. Though we still need to
do a careful assessment, we believe the measured deviation will
prove satisfactory. The last optical-chicane dipole is due to
be received next week. All of the magnet measurements on these
magnets (Hall-probe measurements and dipole-field mapping) are
slated to be complete by 24 Aug. 97. We suspect that the machining
and assembly tolerances at the vendor (Everson Electric) can be
improved, which in turn should improve field-profile deviations
in future deliveries. Consequently, we are sending a Jefferson
Lab staff member to Everson Electric early next week to review
and discuss manufacturing procedures and resolve related questions
that have recently arisen there in regard to assembling the injection/extraction
dipole magnets. Everson Electric now has the parts and are ready
to assemble the first article of this dipole type. At the vendor's
(Magnet Enterprises) request, we ordered more conductor for use
in manufacturing the two 180-degree dipole magnets.
Design of the skew-quadrupole magnets is in final detailing.
They will be manufactured in-house at Jefferson Lab. The quadrupole
magnets for the energy-recovery dump line are all in final assembly
at New England Technicoil and are slated for delivery in about
10 days.
Design of the air-core corrector magnets that are to be mounted
on the beam-position monitors is complete.
Stands and girders for the straight-ahead dump area are on order, and all of the vacuum components supporting first light are either on order or in fabrication. Girders for the X and Y vacuum chambers and for the double-quadrupoles are in assembly. The straight-ahead dump was successfully brazed and is in final welding.
Fabrication of the insertable dumps is about 1 week away from
brazing of their main-body components. Designs of the stands
for the insertable dumps and scraper are complete. Regarding
the electron-beam scraper, the assembly drawing for installation
of its cross is complete, and the design of its main body is once
again in progress after being on hold for three weeks to accommodate
higher-priority design activities.
Concerning vacuum chambers, four of six optical-chicane chamber
components are complete and ready for installation, and the other
two chamber components are at the Magnet Measurement Test Stand
where they are being used to assess the effect of the vacuum chambers
on the field profiles of the optical-chicane dipole magnets.
For the recirculation arcs, the straight vacuum-chamber components
are in fabrication (two are tacked), and the curved vacuum-chamber
plates are due in from the vendor next week.
Regarding cryomodule fabrication:
Work focused on cabling for the installed cryomodule instrumentation.
Instrumentation will support cooldown, commissioning, and operations.
Planning for commissioning the cryounit and cryomodule continues.
Regarding RF systems:
Both of the 8-unit klystron power supplies built by Hipotronix were received and moved into the klystron gallery in the FEL Facility. Prior to this, the #2 power supply was run to full power at the factory and passed our acceptance tests.
The remaining (second) 50 kW RF system was moved from the ITS
into the FEL klystron gallery.
We are still awaiting final shipping instructions from Russia for our failed spare klystron. It is worthwhile to note that almost all factories in Russia are closed for holiday the entire month of August. Any communications are extremely difficult. However, the spare 50 kW RF circulator was tested with the klystron in the ITS prior to its move, and passed our acceptance criteria.
Regarding instrumentation and control systems:
Installation activities included cable pulls for analog monitoring,
video distribution, cryomodule instrumentation, beam position
monitors, and control room patches. The vacuum cables will be
installed next week.
In preparation for cool-down of the cryomodule the temperature
diodes were wired in and connected through the control system.
This is the first complete test of the new server configuration,
input/output controllers (IOCs) and network. All seems fine.
All IOCs have been installed and are operational. The servers
denoting FEL1&2 are running fine.
Design work centered on analog monitor system with the check prints
for the backplane done and a prototype board for the input buffer
board in test. Work is also progressing on the dump instrumentation
and interlocks.
The WWW site for the FEL Facility is progressing rapidly with
individual channel assignments being added for the VME boards,
and system layouts being added for the accelerator enclosure.
FEL Systems
Wiggler
Another clearance problem in the wiggler vacuum chamber support
was found. The T-bars were then sent out to be modified. The
plates for the wiggler girder were lowered by one inch and regrouted,
and the wiggler was reinstalled and surveyed into its final position.
Optics
Two significant accomplishments occurred this week. The first
was the successful indium braze of a test mirror in a mirror holder
without its cracking. The second was final alignment of the last
three mirror cans in the accelerator enclosure. We are transporting
a He-Ne upstairs to the Optics Control room with very little (not
visually apparent) vibration. We are close (~ 1 week) to installing
connecting bellows and the optical components in Optics Control.
The optical cavity assemblies are nearly complete, we are awaiting
particulate tests on the valves. We must also open up the i.d.
of the gimbal mounts, they were made slightly smaller than spec.,
and this slipped through the inspection process. This will cause
a slip of less than a week. We received a verbal report from
China Lake on the metrology results for the sapphire cavity optics
made by Research Electro-Optics (REO). The results show all of
the radii of curvature are longer than the spec (0.2%); the mirror
figure was also out of the tenth wavelength spec. We've sent
one mirror to REO for immediate inspection, China Lake is preparing
to send the others. We received one set of cavity optics from
Rocky Mountain Instruments, they will be sent to China Lake this
week.
Commissioning/Operations
Additional simulations of the beam dynamics from photocathode
to wiggler were completed. These simulations concern bunch charges
for first light (60 pC) and "zero" current. In particular,
the beam dynamics were assessed at these lower bunch charges given
the machine setup for full-power runs, e.g., 135 pC bunch charges.
The 135 pC settings appear adequate for both cases; the 60 pC
case actually looks better with the 135 pC lattice than does the
135 pC case itself. Code results indicate we will need to be
careful about setting the first solenoid (to 280 G) because the
results are sensitive to this setting, degrading rapidly as the
solenoidal field is increased above 280 G. As a matter of principle,
we will also need to check stray fields after the cryounit to
ensure they do not interfere significantly with the very weak
fields of the quadrupole magnets on the injection line.
Work continued on the performance integration plan for RF systems.
The simulations feed into this plan by establishing baseline
RF settings and specifications for their sensitivities. Delineating
the sensitivity specifications is the current priority.
Facility
Punch list work continues (180 items and counting down) as does
site grading. The fire alarm and sprinkler system were tested.
There are a few things to fix but the system is operational,
although it reports only locally. Touch-up of tile work was done,
and a display case was installed in the entrance lobby.
Jefferson Lab folks did lock-down positioning of the optical transport
lightboxes, and they made preparations to cut the pipe and weld
the flanges in place. The wiggler was placed and surveyed into
the correct final position. Cables were pulled into position
for the beam position monitors. Survey located the positions
for all of the arc stands in preparation for setting them.
Cabling to the cryomodule is being terminated. Cool-down of the
cryomodule has been delayed to early September, coinciding with
a CEBAF maintenance day, to avoid the possibility of interference
with the nuclear-physics accelerator. The large high-voltage
power supplies for the 8 kW RF system that drives the cryomodule
were placed in the RF gallery, and hookup began. Some shipping
damage (broken resistors, etc.) was discovered which will require
a site visit by the vendor to repair.
The gas-insulated high voltage power supply for the photocathode
gun was tested this week at atmospheric pressure. We were able
to hold 200 kV continuously and about 220 kV for short periods.
Our design goal was 180-200 kV. This is an important test data
point for us, because it is the basis for extrapolating by a
factor of 4 to 5 to the final design voltage with pressurized
SF6 gas. The elbow for the coaxial line to the gun was received
but did not pass inspection and was returned to the vendor for
corrective action.
Clean Air Technology certified the clean room. The waveguide
for the buncher was installed. The second 50 kW klystron and
power supply were moved to the FEL Facility. The final stand
for the drive laser transport line was signed off, and the other
stands were ordered for delivery 29 Aug. 97.