MEMORANDUM
To: J. Albertine, D. Helms, W. Skinner
cc: Division (M7), FEL Coordination Group
From: F. Dylla
Subject: IRFEL Weekly Report, August 25-29, 1997
Date: August 29, 1997
Management
This was a busy and productive week for FEL installation and sub-system
commissioning activities: the linac cryomodule was successfully
cooled and remains stable at 2K; the completed injector dump beamline
was put under a warm nitrogen purge prior to pumpdown next week;
the initial check-out of the Personnel Safety System (PSS) was
successfully completed; the first arc stands were installed; and
the recirculation dump was installed.
Final revisions were collected on the first set of IR FEL proposal
summaries that will be forwarded next week to the DOE-BES program
office.
A meeting was held on Wednesday of the ARC University Coordinating
committee to discuss the final lay-out of the ARC Building laboratories.
We were able to co-locate many similar activities between the
four universities and Jefferson Lab, particularly laser/optics
labs and materials analysis labs that will have obvious benefits
to FEL users, FEL development and Jefferson Lab R&D activities.
The ARC universities are making plans for moving into the ARC
Building at the end of the calendar year.
We confirmed the attendance at next month's SURA/DOE Science and
Technology Review (Sept.17-19) of Steve Laderman, from Hewlett
Packard Research Laboratories. Steve will be reviewing both the
FEL program and the laboratory's relations with industry. In
his position at Hewlett Packard, Steve oversees the company's
interests at the Stanford Synchrotron Radiation Laboratory.
Accelerator Systems
Regarding the beam-transport system:
Optical Chicane Dipoles - The eight optical chicane dipoles continued
their measurements on the measurement stand with the results showing
that five are acceptable if the calibration of the stand is correct.
Three exhibited unacceptable increase in the field integral at
one edge of the 9 cm required good field region. On that side,
the field integral rises to 2.5 parts per ten thousand at 100
amps (Though the rise in integral is not seen at 200 amps - the
one-additional-cryomodule-upgrade current). We went through a
round of flipping the position of the field clamp plates end for
end on one of these outlyers. The results first indicated that
the magnet joined the population of good magnets with later measurements
indicating that it reverted back to its original increase in the
field integral at one edge. Suspicious that the variation is
an artifact of the measurement apparatus, we are ending the week
with the a full set of measurements with the entire magnet flipped
end for end in the apparatus. Interpretation of the results awaits
Jeff Karn's return on Tuesday. As soon as we achieve a greater
level of confidence in the measurements and have a handle on correcting
the outlyers, we will pin the field clamps in their final position
and authorize installation of a group of four. We will use one
of the remaining four to use as a second reference dipole in a
series of tests to obtain absolute calibration of the standard
dipole and the data set.
Other Dipoles - All the gluing of the Injection/Extraction DU/DV
style dipoles' mu metal/brass shims was completed this week at
Everson Electric and the first magnets of each were shipped.
The core slabs for the 180 degree dipoles are being pinned together.
They are slated for delivery early next week. The first of the
180 Degree dipole coil sets was potted this week. The bids for
assembly of these dipoles are due at COB Tuesday, so we will know
where to ship the coils, cores and parts coincident with their
availability. The remaining parts of the 180 degree magnet measurement
apparatus are out for bid, requesting a late September delivery.
In the quadrupole and sextupole area, winding of coils for the
eight Panofsky trim quads continued at Magnet Enterprises International
(MEI). The three quadrupole magnets for the energy-recovery dump
line (QIs) continue in final assembly at New England Technicoil
with delivery delayed to early next week because of come inconsistencies
in the size of the specified coil positioning fillers.
In the corrector area, manufacture of the coils for the phasing
dipoles (DGs) was delayed at MEI because of the late delivery
of rectangular conductor. Manufacture of the mu metal cores for
phasing dipoles (DGs) and reverse bend correctors (DF&DCs)
is still unsettled, awaiting bids from the mu metal supplier.
Coils for the reverse bend correctors are out for bids due at
COB on Tuesday.
Drawings for the air core corrector coil sub assemblies have gone
through a second back check with refinements resulting from experience
in building the prototype DB. The drawings are due for signature
on Wednesday. The prototype horizontal air core corrector was
completed and the magnet mounted in the test stand. We intend
to run the pivotal cross talk test that duplicates the intended
proximity to nearby quadrupole's iron by drawing sign-off time.
Passing the cross-talk test is needed before approval. Design
of the skew-quadrupole magnets remains in final detailing.
Some optical chicane chambers are going through a second cycle
of cleaning (which will require an off-line bake) after large
particulates were found in one. The particle counter test employed
earlier detects small particulates only and didn't detect this
class of contamination. This incident redoubles our vigilance
during tube cleaning.
Chamber welding - Inspection revealed problems that required scrapping
two bodies of the five straight reverse bend chambers. Parts
for recovery are due next week as the welding manpower for these
critical elements was increased to three qualified welders.
The remaining three bodies are machined to accept flanges. The
seven curved reverse bend chambers are at 15 % completion using
improved procedures. The parts for chambers for the 180 degree
dipoles are now complete at Master Machine and they are developing
weld procedures on samples using argon hydrogen mixture for shield
gas, a significant advantage for welding this thicker joint.
The first articles for stands for the arcs arrived this week and
are installed.
In the power supply area, the two power supplies for injection
and extraction dipoles have been shipped by air freight with customs
inspection requiring an additional week before we receive them.
The remaining probes for zeroing the dipoles at the dumps were
received and the electronics for the systems are on hand. Brackets
to mount the probes remain at the concept level but are considered
to be easily created.
In the installation area, the entire beam line in the injector
to its dump region is under vacuum and robust. The line downstream
of the cryomodule and into the recirculation dump is now receiving
assembly attention.
Regarding cryomodule fabrication
Cryomodule
The installed cryomodule is cooled down and filled with 2 K helium.
The cryomodule is operating at 2 K and will start preliminary
check out next week. Full RF commissioning will begin when RF
and safety systems are operational.
Warm Windows
The warm window program continues to progress on three fronts.
The primary program, modification of a cold window to the warm
location, has had a successful resonance ring test of a completed
window to 50 kW cw RF power. The heating was limited to 90 degrees
celsius on the ceramic and 45 degrees celsius on the flange. These
temperatures are well within requirements. This window suffers
from a vacuum leak that is not related to RF power operations.
Additional windows are in fabrication at this time and are not
expected to leak. The remaining two efforts are making progress
toward completion of prototype assemblies. Prototypes should be
available for evaluation during September.
Regarding RF systems:
The elbow for the 500 kV High Voltage Power Supply was installed
for pressure and high voltage testing. We ran atmospheric pressure
high voltage tests on the and were able to hold 150-160 kV. This
meets our requirements, but without a lot of margin. The Cathode
Power Supply wiring continues for the required PSS interlocks
of the Buncher system. The RF system for the Buncher is about
50 % complete. The installation of the 50 kW klystron systems
for the quarter cryomodule is about 50 % complete. Hipotronics
technicians made the necessary repairs to the first 225 kW Variable
Power Supply. AC power will be connected next week to allow high
voltage testing. Hipotronics will send people back to repair
the second unit after the first unit has been high voltage tested.
The RF system for the linac is about 40 % complete. The Master
Oscillator (M.O.) is ready for phase noise testing with the drive
laser. Insulation for the LCW pipe and M.O. distribution cables
were received today. The M.O. system is about 80 % complete.
The SOP for operation of the 50 kW RF systems is complete and
ready for use.
Regarding instrumentation and control systems:
All of the beam viewers, BPM's and multislit from the gun to the
injector dump are installed. The installation of peripherals
will commence post bake-out. The 100mm camera lenses are beginning
to arrive, all of the CCD cameras are here and being checked out.
Talks are ongoing with Princeton Plasma Physics Laboratory to
borrow their polychromator to analyze bunch rms bunch length of
the FEL electron beam.
The PSS certification went well, a short punch list is being worked,
the wiring and remote interfaces are being finished up this week.
The instrumentation for the dump water skid is being assembled,
this will be run in early September.
The vacuum system control cable pull is complete. These are being
terminated now. The software controls checkout will start next
week.
The AMS backplane board is due back from fabrication next week.
One potential hold up is the delay in shipping of one of the
card-edge connectors, we are working this. The production AMS
buffer board prototype is complete and being evaluated, this should
be ready for production next week. The analog-to-fiber chassis
arrived, the initial tests are disappointing, the frequency response
falls short of 1 MHz. This unit is used to transmit the AMS signals
to the MCC (~.5 km). Internal to the FEL building the AMS is
flat to over 20 MHz.
The DC power trim racks are being powered up and checked out.
After the bake-out of the injector is complete, the magnets will
be connected and field polarity checked.
FEL Systems
Optics
Work continued this week on the drive laser and the optical system.
The laser's delivery optics are complete to the Brewster window
in the Clean Room. A He-Ne laser collinear with the drive laser
beam is used to align the transport optics on the ground floor.
We discovered two of the stands were designed for the wrong elevation,
these have been modified. The first mirror can is hung and aligned,
we are proceeding with alignment through the telescope box. The
two cans being built by the Machine Shop are being cleaned before
welding. The drawing for the mirror cassettes and stands are
signed and in Procurement. We are nearing completion on the design
for the insertable dumps. We discovered that the molybdenum mirrors
for the optical collimator were figured incorrectly, they are
going back to the vendor for repolishing. We will temporarily
use mirrors dielectrically coated for 633 nm. We received the
5.5" dia. window needed in the upstream optical cavity assembly,
the entire assembly is nearly complete. Michelle Shinn had a
video conference with staff in the physics branch at China Lake.
This group does the metrology on our optics. She answered questions
about the specifications for the IR Demo FEL, and participated
in a discussion on how to quickly get better optics. Of the several
action items that came out of that meeting, those for Jefferson
Lab personnel await the return of staff on travel at the International
FEL Conference. She also learned that a test set of mirrors made
by Rocky Mountain Instrument met specifications for reflectivity.
They will begin measurements on the scatter next week, that value,
combined with the reflectivity will give us a value for the coating
absorption.
Commissioning/Operations
The second meeting of FEL principal investigators was held and
along with discussion of PI duties and responsibilities, a list
of personnel assigned to each task for the commissioning was generated.
The Commissioning meeting discussed progress of the magnet performance
integration plan and then used the present DW magnet measurements
as an application/test of the process. The DW measurements indicate
integrated field flatness errors on three of the seven magnets
measured at 2.5 to 3 times the level of the specification. From
the integration plan perspective, the magnets allowed us to use
the criteria stated for when a magnet is good enough; i.e. can
it be modeled? is it reproducible? etc. They provided a good
first test of how magnets that fall outside the specification
should be handled.
The injector dump setup procedure was completed and modeling is
continuing on the buncher and cryounit fine setup procedure.
Facility
The majority of activities in the facility this week focused on installation items noted above in the system reports. We continue to improve the housekeeping in the accelerator vault as the vacuum system activities are ramped up. Floor areas are being cleaned, all non-necessary installation material is being removed, and additional mats are being laid in front of all building entrances. A meeting was held with the contractor to resolve the improper leveling of the floor near some of the perimeter drains which will help floor cleaning exercises when resolved. The contractor continues to deal with equipment needed to certify the elevator. All other punch list items are minor.