IR FEL Monthly Report for August 1997
Navy IR Demo Contract WBS Elements
WBS 1 Project Management
August 1997 was the fourteenth full month for the IR FEL Demo
project funded by the Navy.
Cost Performance Scheduling
We have expanded the discussion of cost performance/scheduling
in this monthly report as the project nears completion.
The original project total available budget was $8,082k. As discussed
in last month's report, a funds transfer was negotiated with
LANL for $37,645 for an FEL modeling task, reducing the total
available budget to Jefferson Lab to $8,044k. This month's assessment
includes this performance and the cost of the work. Performance
was taken under the Management account as part of the "contingency"
pegpoint while the Optics account, where the work was performed,
accrued the cost. The project was always fully scheduled.
The IR FEL Demo project through the month of
August 1997 has a total of $7,789k (less SRF and the building)
of performance scheduled. The work performed through the current
period is $7,312k or 90% complete versus 96% scheduled. The actual
costs accrued through August totals $7,358k. This results in
a negative schedule variance of $477k and a negative cost variance
of $46k.
As of the end of August 1997, $7,903k has been
costed and/or obligated ($7,358k in actual costs and $545k in
current obligations). The remaining unobligated balance is $179k.
A plan is in place to fully obligate/cost these funds not later
than September 30th. The cost for LANL support ($38k) has been
included in the costs and performance quoted in the previous two
paragraphs.
One month remains to accomplish the remaining
scheduled work of $770k in the project's Performance Assessment
"Earned Value System". This represents an increase
of $51k per month over the July average of $619k.
Management
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 of the second Navy-DOE Memorandum
of Agreement for the IR Demo Project.
Scheduling activities are focused on carefully integrating the
remaining installation tasks with the start-up of commissioning
tasks. Installation tasks are being phased such that remaining
installation tasks will have little or no impact on the first
commissioning tasks which will proceed from the gun to injector
cryounit to linac cryomodule to wiggler to recirculation arc.
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. At month's
end, final revisions were collected on the first set of IR FEL
proposal summaries that were forwarded to the DOE-BES program
office.
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 FEL project was presented in papers at the International FEL
Conference in Beijing in August. The following papers were given
by project staff:
"Status Report on Jefferson Lab's High-Power Infrared FEL"
- C. Bohn
"Progress on the Study of Emittance Growth Induced by Transient
Self-Interaction of a Bunch Entering a Bend" - R. Li
"Experimental Results from a DC Photocathode Electron Gun
for an IR FEL" - D. Kehne
"Optical Modeling of the Jefferson Laboratory IR Demo FEL"
- S. Benson
"Real-Time Transverse Emittance and Phase-Space Monitor"
- J. Song
Congressman Bateman's Office requested an update on the current
status of the FEL project. A telephone briefing to the Congressman's
staff was followed by a brief written summary of the conversation.
A meeting of the ARC University Coordinating committee was held
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 the 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.
WBS 5.0 Instrumentation & Controls
Regarding instrumentation and control systems:
The bulk of the beam instrumentation mechanical devices are being
installed or are on the shelf. 18 of the 25 stripline Beam Position
Monitors (BPMs) are installed, none of the "button"
BPMs have been installed since those vacuum chambers are not yet
complete. All of the BPM cable assemblies are installed, these
were purchased complete with terminations and cable labels. The
electronics are being installed in the control racks. 10 of the
24 Optical Transition Radiation (OTR) beam viewers have been installed;
of particular note these viewers use a 1.5 micron Al foil as the
flag. This has proven to be problematic in the past but by using
new tooling the foil is able to be stretched slightly ensuring
a flat surface. All of the beam viewer cables are in place, some
of the video cables still need to be terminated. The "Happek"
devices are coming in under the original cost estimate so we are
exercising the option to purchase the third unit. They will be
here in early September for a trial fit-up with the stands in
the tunnel.
In preparation for cool-down of the cryomodule the temperature
diodes were wired-in and connected through the control system.
This was the first complete test of the new server configuration,
input/output controllers (IOCs) and network. The server computer
(ITSserv) is still operational, this was brought over from the
injector test stand to facilitate rapid startup of the drive laser
systems and support RF commissioning. All IOCs have been installed
and are operational. The servers denoting FEL1&2 are running
fine. The controls network hub had a slight problem recovering
after a scheduled power outage, this was quickly rectified. These
start-up problems are expected and are being worked out.
Design work is centered on the Analog Monitoring System (AMS).
The system prototype boards are working well, the system is running
with flat response out to >20MHz local to the FEL building.
The commercial unit used to transmit the analog signal from the
FEL building to the Main Control Center (MCC) has a rolloff at
1 MHz (-3dB) (unfortunately). This will be sufficient for commissioning
but may be considered for an upgrade in the future. The input
buffer boards are out for production, the backplane boards have
been delivered; these are four layer printed circuit boards with
both a data and address bus. This backplane board was designed
with the flexibility to also be used in drive laser, RF diagnostics,
and beam instrumentation future applications. The multiplexer
is common to both the AMS and the beam viewer video system (and
the optics video). The chassis contains four 16 X 16 video crosspoint
switches, these have wired-ORed outputs. The video system requires
64:16 and the AMS requires 128:16, the muxing system is designed
to be expanded to 256:16 by simply adding the 64:16 building blocks.
Another advantage is that the software drivers are common for
both systems. This eliminates the additional load on the software
group. The VME based driver is the same board that we designed
for the Drive Laser Pulse Controller (DLPC), the interface between
the DLPC VME board and the video muxes has been prototyped and
is being used by the software developers. When the design is
verified this will go out for production.
Work continues on the dump instrumentation and interlocks. Most
of the parts are in-house, the final design is not yet complete.
This will be finalized in early September and the required control
chassis will be constructed.
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.
The home page for the documentation and engineering can be found
at http://www.jlab.org/accel/fel/documentation/evans/felbair1.html.
This site is updated on a daily basis reflecting the ongoing
installation activities. This site also serves as a database
for information on spares and system failures.
The control and readout chassis for the 500 kV gun power supply
is in fabrication, this will be installed and tested mid-September.
This buffers the drive and readout analog signals for the control
system, interlocks the HV to vacuum and provides a remote interface
to the control system.
The PSS has been certified, the process will continue as the peripherals
are brought on-line. The RF system will be connected to the PSS
interlocks when the waveguide shorts are removed and the klystrons
are connected to the SRF cavities, likewise the gun high voltage
power supply will be connected after the gun bakeout is complete.
The Machine Protection System (MPS) design review was postponed
due to personnel conflicts with the main accelerator. This will
be held in September. The system installed from the Injector Test
Stand is sufficient for beam operation through December when the
average current is to be raised to 1 mAmp.
All of the vacuum system control cables have been pulled, the
cable tray has had dividers mounted to segregate the high voltage
cables from the balance of the cables. An additional cable tray
was installed to correct for an under estimate in the loading
of the 12 inch power tray. There was not proper clearance for
cooling of the 535MCM main dipole cables. All of the ion pump
power supplies are mounted as well as both of the vacuum control
crates. The software controls are in the works, total system testing
will begin in mid-September.
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. The two large box supplies
are ready and waiting for magnets.
The access control hardware for the user lab safety systems is
arriving and being checked out. Magnetic locks are being installed
as well as the PLCs. The access and Laser Safety System (LSS)
will be based on Smart Card technology. Each user and JLab employee
requiring access to any of the laser areas will be issued a card.
When any smart card is presented to a reader, the database will
be checked for relevant information on safety training particular
to a specific area, at that point the magnetic lock will be released
and the persons name will be recorded as entering a given area.
This will allow for easy access throughout the building without
relying on administrative controls to prevent accidents.
WBS 7 Beam Transport
Among recirculation dipoles, the coils for the 180 degree dipoles,
with three of four wound, are the only parts not on-hand. The
reverse bend dipole hardware is at the assembly vendor for final
fit-up. All eight optical chicane dipoles are completing magnetic
measurement. They have passed all tests except three remain to
be adjusted to meet the one hundredth percent uniformity of the
field integral over the good field region. We are confident this
specification can be met.
Quadrupole acquisition will be complete with delivery of two styles
of Panofsky trim quadrupole (11 magnets), expected next month.
In the corrector area, three mu metal styles have been delayed
in manufacturing by about a month by manufacturability questions
but have restarted. The three styles of air core correctors were
detailed, checked and are near sign-off.
In the vacuum system, the optical chicane chambers were completed
and welding started on the chambers for the arcs around the reverse
bends while the parts for chambers for the 180 degree dipoles
were completed.
Design of all stands and girders was completed.
Installation activity continued to concentrate on the injection
line and its dump as the vacuum pipe was closed and its conditioning
for high vacuum started. More enclosure cable tray was installed
as room in the existing tray was exhausted.
Overall summary: 180 degree dipole completion and the measurement
of all remaining dipoles and correctors remain on the critical
path. Manufacturing chambers is now off critical path. From
another point of view, we now have great confidence in meeting
beam transport magnetic element requirements. Measurement of
the batch of DW dipoles proved that the spectrometer-dipole-like
specifications can be met, after some adjustment, with magnet
sets of the style we are building. Manufacturing the dipoles according
to project specifications and proving it with appropriate measurement
slowed the installation process and forced schedule slip, but
the slip in installation of the remaining magnets will not impact
the start-up of commissioning.
WBS 8 RF Systems
In the Injector, zone 1, the RF systems for the buncher and quarter
cryomodule are nearly ready for RF testing into waveguide shorts.
They will be operated first in local control and then remote
under software control. The software and low level RF racks for
the Injector have been used to test the phase stability of the
drive laser. In the Linac, zone 2, testing of the low level RF
control system was halted to concentrate on the Injector zone.
After repeated calls to the vendor concerning the failed spare
50 kW klystron, we are still waiting for directions for additional
testing or return instructions. Both Hipotronics and the 225
kW variable DC power supplies were received this past month.
Both units sustained shipping damage. The first unit was repaired,
installed, and preliminarily tested. The second unit will be
repaired after the first unit is load tested, so that all repairs
and any changes can be made at the same time. Except for a small
amount of insulation in a presently unused zone, the Master Oscillator
installation is complete. The new Divide by 40 chassis was installed
and preliminary tests were started on the phase stability of the
drive laser system. The location of the buncher water skid is
being moved again due to space requirements of other equipment.
It is to be connected and tested next month.
WBS 9.2 Injector Move
The vacuum system between the gun and the injector dump was completed,
installed, and ready for leak-check by month's end. The design
of the upstairs stand for the drive laser transport was completed.
The stands for the mirror cans downstairs were received and installed.
Two of them had to be modified slightly to account for a design
error. Two of the transport cans were installed. The high voltage
power supply was tested in air with just the power supply in the
tank and then with the elbow to the gun installed. The former
test was quite successful but the second test indicated that some
work reducing corona in the elbow was necessary. The gas system
for the tank was mostly installed by month's end. Substantial
work was completed on installation of the RF systems. All three
systems were installed with the exception of some waveguide and
a great deal of the wiring and checkout was completed by month's
end.
WBS 9.4 Wiggler
The wiggler girder was installed and aligned. Pulsed wire measurements
of the girder indicated that the four quadrupole magnetic centers
were well aligned with each other. The trajectory indicated by
the measurement was very close to that calculated from the STI
Optronics magnetic measurements indicating that the wiggler was
not damaged in shipping. Test pieces for the wiggler vacuum chamber
were electron beam welded successfully.
WBS 9.6 Optics
This month we completed assembly of the downstream optical cavity
assembly (save installation of the pellicle viewers) and are nearly
finished with the upstream assembly. We successfully indium brazed
a test mirror in a mirror holder without its cracking. We tested
the LVDT readouts for the gimbal mounts, finding there is negligible
backlash in the yaw plane, and that the LVDT had sufficient resolution
to assist us in maintaining the cavity mirrors orientation. We
learned that our sapphire mirrors (coated for 3 microns by Research
Electro-Optics (REO)) have radii of curvature longer than spec
(0.2%). A test set of mirrors made by Rocky Mountain Instrument
met specifications (> 99.7%) for reflectivity. This is a promising
development, since RMI is making our first light mirrors. The
FEL optical transport line is complete up to the Optics Control
Room on the second floor. The stands for the transport line on
the second floor are complete, and the pipes have been cut to
length and the flanges welded to them. Design for the mirror
cassettes is complete and in Procurement. We received the complete
order for the Brewster output windows for the User labs (six plus
four spares). We've built power supplies for the vidicon cameras
that will be used for the cavity alignment, and studied the linearity
of the Cohu CCD cameras used for both the optical and electron
beam transport viewers. The drive 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 hung one mirror can and modified
two stands that were designed incorrectly. The drive laser is
undergoing checkout, and is operating nominally.
Injector, SRF, Facility, and Other
Activities Outside Navy IR Demo Contract
INJECTOR TEST STAND
WBS 3 - CRYOMODULE
Linac Cryomodule
The linac cryomodule was aligned and successfully cooled to 2k.
Warm Windows
The cryounit of the IR FEL's injector requires higher power warm
RF windows than does the standard CEBAF cryomodule. Specifically,
the requirement is for 50 kW windows in the cryounit, which is
needed to drive a 5 mA cw beam current through the superconducting
RF cavities. This is an order of magnitude higher than the requirement
for the CEBAF cryomodule warm RF windows.
As currently installed in the FEL Facility, the cryounit is configured
with ceramic warm RF windows that have been qualified to 10 kW
of cw RF in full reflection. This reduced power limit is a result
of problems with the thermal control of the warm windows which
is driven by excessive dissipated RF power in the ceramics. These
windows have been run with cw RF power up to 50 kW traveling wave
in our Resonant Ring Test Facility and run at 10 kW full reflection
in the cryounit in the Injector Test Stand cave. These power
levels are appropriate for supporting first-light IR FEL operations
which are projected to continue well into Spring 1998.
The root cause of the warm window limitations has been the RF
performance of the ceramic material used in the windows. The
material originally used was developed to support the cold RF
window production for CEBAF and had demonstrated appropriate warm
RF characteristics at that time. Changes in material performance
since that time have resulted in a requirement to develop a new
supply of ceramic for the present application. This has been
done and windows are now in production using this material. Three
windows have been produced with this material and tested up to
50 kW cw traveling-wave power in the Resonant Ring Facility.
The thermal performance of these windows has been greatly improved
and is acceptable for FEL operations. Additional ceramics are
now being procured and will be used to produce four windows for
full-power qualification.
Two additional efforts are being pursued in parallel to ensure
a robust solution to the warm window requirement. The first is
a collaboration with Northrop Grumman that has resulted in a new
design using a BeO window material in a two-piece flange assembly.
We completed the first of these assemblies on 12 Sep 97 and are
evaluating it now. The second effort is a new design being developed
in-house. It incorporates a water-cooled waveguide mounting of
a ceramic window and has potential for even higher-power applications.
All required parts for a prototype assembly are in procurement
and are due to be received in the next two weeks.
The requirement for the full 50 kW RF windows to support operations
is coupled to kW-level operation with 5 mA cw electron beam, which
will probably begin not earlier than May 98. Operating plans
for CEBAF and the IR FEL accelerator include a shutdown in Jan
98, at which time there will be opportunity to change the warm
windows on the cryounit. Production and qualification of warm
windows are therefore scheduled to support a Jan 98 changeover,
and sufficient in-house resources are in place to support the
schedule. The windows will be qualified on the Resonant Ring
Test Facility and a test fixture being powered by one of the 50
kW klystrons in the FEL Facility. This test fixture is already
installed there.
WBS 2 -- BEAM PHYSICS
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 settings 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.
Considerable modelling of the longitudinal-phase-space experiments performed in the Injector Test Stand was done, and the results were summarized in a paper entitled "Experimental Results from a DC Photocathode Electron Gun for an IR FEL" that was presented by D. Kehne at the FEL Conference in Beijing. The longitudinal measurements are noteworthy for their general agreement with PARMELA, though there are differences in certain details of the longitudinal phase space.
The procedure for establishing RF phases of the cavities in the
cryomodule to facilitate energy recovery underwent further investigation,
culminating in a technical note entitled "Fine Phasing for
the Cryomodule Using the Energy Recovery Dump". Modelling
also proceeded to support development of detailed ("fine")
test plans for commissioning the injector, with the basic goal
being to identify the diagnostic which is most sensitive to each
parameter of the bunching/acceleration devices.
Simulations were done to aid in establishing a procedure for transverse
emittance measurements using the quad-scan technique in the wiggler
line (between the two chicanes), before the first recirculation
arc, and in the backleg. Multimonitor measurements in the backleg
using the 6 optical transition radiation (OTR) detectors, and
in the wiggler line using the 5 OTRs, were also done. These simulations
support the development of test plans for the coherent synchrotron
radiation (CSR) experiments. The foundational test plan for measuring
the emittance before and after the first recirculation bend is
complete, and we are working on the test plan concerning the bunch
decompressor. Concerning theoretical developments, R. Li presented
a paper at the FEL Conference in Beijing entitled "Progress
on the Study of Self-Interaction of a Bunch in a Bend" which
describes new analytic results concerning noninertial forces that
arise off-axis from the design orbit.
WBS 4 -- IRFEL COMMISSIONING/OPERATION
As one of the preparatory steps for commissioning the IRFEL, performance
integration plans were drafted for RF systems, magnets, and electron-beam
diagnostics. In essence, these plans identify both the associated
tasks and manpower requirements/skills. In general, they are
based on modelling results like those mentioned above under "Beam
Physics", since simulations are generally used to specify
hardware requirements and tolerances.
A spinoff from considering the performance integration plans is
a list of software requirements for high-level applications.
In some cases, this software is either already available from
the Injector Test Stand or nuclear-physics machine, or under development.
However, some of the high-level software had not yet been programmed
for development, and in these cases we made plans to rectify the
situation.
The installation and commissioning schedules were developed up
to the first-light milestone. We are presently considering whether
to plan for circulating a low-average-current beam all the way
around the machine prior to Christmas. Advantages for doing so
include ensuring all remaining installation activities are completed
this fall and identifying hardware problems prior to the scheduled
January shutdown so they can be rectified during the shutdown.
Disadvantages include postponement of detailed experiments on
parametric sensitivities of machine settings and on CSR until
February. Although we have yet to make a final decision, we are
leaning toward adopting this plan in view of its advantages.
Difficulties obtaining consistent field profiles among the optical-chicane
dipole magnets now appear to be largely resolved. The profiles
are very sensitive to the locations of the field clamps. Consequently,
with the aid of differential field measurements in the Magnet
Measurement Test Stand, we determined the necessary field-clamp
locations on each of the eight dipoles and pinned the clamps in
place. We will soon release the first set of four optical-chicane
magnets for installation in the FEL Facility in early September.
Our experience with these dipoles has resulted in a procedure
for checking out and adjusting the other dipole types that will
follow, and therefore we are hopeful that certification of these
remaining dipoles will proceed more expeditiously.
Facility
The facility is essentially complete. There is still some punch
list item activity going on. The only major open item is installation
of an electrical relay which will permit the elevator to pass
code and be operated normally. Negotiation of final cost will
occur after the punch list is complete.
Upcoming Meetings and Reviews
SURA Science and Technology Review, Sept. 16-17, 1997 (Jefferson Lab)
Construction Project Close-out Meeting, Oct. 2-3, 1997 (Jefferson Lab)
Scientific Opportunities for Fourth Generation Light Sources,
October 27-29, 1997 (Argonne National Lab)