FEL Monthly Highlights
August 2001

The FEL was operated for the last three weeks of the summer run for microfabrication studies, laser ablation for
carbon nanotube production, UV processing in photosensitive glasses, vibrational energy transfer in proteins ,and
terahertz radiation generation.

At the International FEL Conference held in Darmstadt from Aug. 19-24, high average power FEL's, energy
recovery schemes, and FEL specific applications were well represented at the conference.

Our readers should note that an article on the recent user applications of the IR Demo FEL was just published in
the August issue of Laser Focus World (including a nice cover photo about the nanotube production by the
CWM-Penn State, NASA team).  The article is available at the following website:

We sent out the first procurement package for one of the dipole magnets needed for the upgrade.  Bids were
received this month for fabrication of the Upgrade GW dipole magnets.  They are currently under technical and
cost evaluation.

We have fixed the date for the next upgrade project semiannual review as Nov. 8-9.  Much of project
management’s attention was devoted to budget close-out issues for FY01, and FEL project management plans
and budget projections for next few years were prepared for the Lab’s annual Institutional Planning review by
DOE held on Aug.17th at DOE headquarters.  Papers were prepared for presentation at the International FEL
Conference in Darmstadt.  Presentations that were reviewed and presented at the conference included:  George
Neil's overview of light source development in the last decade and a talk on second harmonic generation in the IR
Demo; Steve Benson's review of lesson's learned with the IR Demo FEL; Lia Merminga's analysis of RF physics
and beam current limits in energy recovered linacs; and Ed Gillman's review of his user experiments with scanning
near field microscopy.  When the accompanying manuscripts have been completed and reviewed they will be
made available on our server.

M. Shinn and G. Neil attended a "Lessons Learned" meeting at JTO in Washington on Aug. 13.  Some initial
results of the laser materials testing were presented.  There is much interest in the results and several modifications
to the test approach for the planned September run were discussed and agreed upon.  A small action item list
was released.

At the FEL Conference in Darmstadt, the FEL Program at Jefferson Lab was well represented.  Both George
Neil and Steve Benson gave invited talks as follow-up to their winning last year's "FEL Prize".  George discussed
the evolution of light source development over the last 10 years with the recent successes with amplifier FELs
(SASE's), high average power demonstrations with energy recovery schemes, and extensions of the energy
recovery concept to next generation x-ray sources.  Steve gave a summary presentation on what we have learned
on FEL related physics and technology development from the IR Demo.  Lia Merminga gave an invited talk on
"RF Stability in Energy Recovering FELs" and Ed Gillman gave a presentation in the FEL User's Workshop on
his work on scanning near field microscopy.  Additional presentations by JLab personnel included:  "Mode
Distortion Measurements" by S. Benson et al; "Second Harmonic FEL Oscillation" by G. Neil et al; "Design
Principles for a Compact High Average power FEL" by L Merminga and S. Benson.  Several papers were
presented by our colleagues from other institutions on work related to FELs at JLab.  Bill Colson's group at NPS
presented two posters on their preliminary simulations of a 100 kW design using short Raleigh lengths and a step
tapered undulator.  Alan Todd at AES gave a poster on the AES model for high average power FELs based on
SRF energy recovered linacs. Conference papers are currently in the review cycle prior to publication.

With respect to the last run of the IR Demo prior to planned December 1 shutdown, we are collecting data from
our internal and external users to use this time most effectively.  External user requests are due on Sept. 15th.
Prior to the external user run which begins in October, we will be running the IR Demo for the second phase of
the JTO laser damage studies and for machine development needs for the upgrade.

We were in frequent communication with our Program Officer at AFRL to help complete the last paperwork for
the start-up of the UV FEL project.

We are analyzing end of year budget projections prior to closing out the Phase1 of the FEL Upgrade Project on
Sept. 30.

Project Cost Performance:
The project (Phase 1) budget for the period June 1, 2000 to September 30, 2001 is $9,029k.  The Phase 2
project was approved for $4,500k for a performance period of February 1, 2001 to September 30, 2002.  The
project through the month of August has a total of $6,310k of performance scheduled (assuming the project
started at the originally planned start date of April 1, 2000).  The work performed through the end of August was
$5,962, which is 66% complete vs. 70% scheduled.  The actual cost accrued through July totals $7,208.  This
results in a schedule variance of -$349k and a cost variance of -$1,246k.  We are on track for having the first
phase of the project fully obligated by the end of September.  (The total project cost to date-actual costs plus
commitments is $8,847k.)  The negative cost variance presently showing is largely an artifact of having to obligate
and cost funds early in the project in order to ensure full obligation and costing by the project end date. We
expect to recover any remaining Phase 1 cost and schedule variances by the completion of the Phase 2 barring
unforeseen difficulties.

The first charges to Phase 2 were accrued this month with $137,400 being spread over WBS 4 through WBS
11.  Starting with the September summary cost performance report, a complete breakdown of charges and
earned value by WBS will be given for the Phase 2 effort.

WBS 3  (Beam Physics):
Three pass beam was circulated through the Demo driver, momentum spread was reduced, and energy
recovered beam was observed at the dump.  Pictures (of 3 passes at the end of the module, 2 in the backleg, and
1 at the dump) are available at:  http://www.jlab.org/~douglas/FEL/configuration_updates/3passvg.ppt .  A tech
note will be forthcoming.

Upgrade octupole specifications were published as JLAB-TN-01-036, which is available online at:

Transverse linac optics for 1 pass CEBAF-ER (energy recovery experiment) were developed and will eventually
be documented.

WBS 4  (Injector):
The GaAs wafer in the existing gun passed the 4k Coulomb delivery mark this month.

The cathode support tube and the cathode stalk were submitted to the machine shop for fabrication.  The anode
support plate drawing was signed off and submitted to the shop for fabrication.  The anode plate polishing was
completed to 1 um.  Signed off the ball cathode drawing and submitted the job along with the material to the
shop.  The external corona rings were received and checked.  The drawings for the cesium channel buses and
charge collection ring have been signed off and submitted to the shop.  The ceramic stack was welded together
and is waiting for leak checking.  NEG pumps for the gun chamber were ordered.  Ordered and received the
material for screens in the gun chamber.

The HVPS Tank for the existing gun was opened to provide the Mechanical Engineer and Designer an
opportunity to take field measurements so the new tank design will mate with the existing Transmission Line and
Gun.  The multiplier stacks were also temporarily assembled for additional measurements to design the new
HVPS Tank.

WBS 5 (SRF):
Qualification of JL008 was completed this month with a final gradient of 16.3 MV/m at Q value of 6.5e9. This
cavity will now be completed with the addition of end groups and a helium vessel.

The helium vessel/end group alignment tooling is being modified to accommodate the latest revisions to the

The new FPC flange testing was completed with successful cryo-cycles to 2 Kelvin liquid helium with multiple
tests. This completes all the flange tests scheduled.

Higher Order Mode testing is continuing on the final positions of the coupler probes.

A second vertical test cavity stand was completed and is undergoing leak checking. This second stand will
increase the number of cavity tests allowing for faster turnaround in this qualification stage.

We have received a very attractive offer from Toshiba for electropolishing the SRF cavities for the upgrade
cryomodule.  A contract will be pursued in the Phase 2 effort

WBS 6 (RF):
Zone 3 - Installed 4 RF Control Modules with 4 test units due this afternoon.  All 8 klystrons, Mod Anode, and
Filament boards were installed.  LCW and Instrument Air were activated for this zone.  Power and control cables
are being wired between the HVPS and the High Power Amplifier (HPA).  Control Power is connected to the

The wiring of the zone is 95 % complete.  EPICS is connected and communicating with the RF Control
Modules.  After  the 5 watt preamps are installed, the zone will be operated into shorts for the first tests.

Zone 4 - Zone 4 - The 8 RF Control Modules and 2 stepper cards are still missing, but AES is working to
replace them.

Quarter Klystrons - September 12th is the scheduled date to witness factory tests of the 100 kW klystrons at
CPI.  The carts for the klystrons are being built in the machine shop.  The three new 100 kW circulators were
tested this month.  They do not yet meet the full specifications as we were able to test them to only 50 kW, but
they appear to be workable.  The vendor is working to help us adjust the Circulator S11 and S21 bandwidths to
be flatter and wider.  The circulators will be tested at 100 kW after the new 100 kW klystrons and HVPS's have
been installed and checked out. Zone 3

Quarter HVPS - Contracts were placed for the new Transformers and Inductors with NRL.  The Rectifier
Assembly was ordered from CKE. The SCR Controller to ramp the HVPS on and off has been ordered.

WBS 8 (Instrumentation):
Parts have been ordered and an area constructed for assembly of beam viewers. Prototype boards for the new
beam viewer camera/lamp board power supplies have also been ordered and a bracket designed for mounting
the power supply and air solenoid to the beam viewer housing.

The OBPM absolute value/sample and hold board has been assembled and a test box built. The OBPM detector
board has also been modified and will be tested along with the sample & hold board.

A 32 channel sample and hold buffer board has been designed and prototype boards ordered.

The programmable delay card has been successfully tested.  There are still some programming issues in EPICS to
be resolved.  This should prove to be a very versatile system once all items have been completed.

Drawing updates continue with several on hold pending final design changes.  All systems currently under
revision/design have been listed in previous reports.

The "Rabbit" programmable TCP/IP controller board was successfully used for the first time.  It was
programmed to interface to LabView for Bob Austin's experiment.  The Rabbit controlled the direction of the
servo interferometer.

Trim rack specifications are nearly complete. The racks will go out for bid for 4 racks; 128 channels with an
option for an additional 128 channel (if $ is available).  The plan is to use the new DSP/4-quadrant trims to
control the iron core magnets and to use the existing trim channels on the air core magnets. The RFP will go out
for complete rack assemblies.

Testing is nearly complete on the VME timing/delay board and EPICS software is being developed to support it.
Prototype boards for the new beam viewer camera/lamp board power supplies have arrived and all components
for the beam viewer control box are on order.  Additional carrier boards have been ordered to be used as new
systems are developed.

An analog differential driver board is also under development for better monitoring of beam current.

The first of the new Ion Pump Power Supplies has been shipped back to the lab for testing.

Testing is nearly complete on the VME timing/delay board and EPICS software is being developed to support it.
Prototype boards for the new beam viewer camera/lamp board power supplies have arrived and all components
for the beam viewer control box are on order.  Additional carrier boards have been ordered to be used as new
systems are developed.

An analog differential driver board is also under development for better monitoring of beam current. The
prototype has been installed and works very well. This reduces the noise on the bunch charge monitor as well as
providing ~1 microsecond rise time to allow fault-free alignment mode operation with macropulses less than 10

The gun high voltage tank SF6 pressure transducer & control room readout has been commissioned and is
operational.  This had been on the "list" longer than most.

The first of the new Ion Pump Power Supplies has been shipped back to the lab for testing.

A digital Input/Output box is being built for use in the labs to allow more functionality and control of test

Drawings completed this month: F0015 - 32 Channel Sample and Hold Board drawings have been revised to
correct the placement of the connectors.  F0060 - VME Timing Main Board was revised to make a minor
change in hole size for the connector and one of the front test connections.  F0094-98 - Temperature  Monitoring
Chassis:  Wiring Diagram, Fabrication, and Assembly Drawings.

The BAIR web and the task system have received several updates.  An "UPGRADE" section was added to
BAIR web for information on the 10kW upgrade.  Anyone with information to post can contact Mike Aston
directly via a link on the site.  The task system has been updated to allow searching for specific tasks by system.
Personnel wanting information on a particular system can enter that system name, and all tasks associated with
that system are available.

WBS 9 (Electron Beam Transport):
Optical Chicane Dipoles (GW)
o  The procurement package was sent to 12 companies for submission of proposals.  We received responses and
    all required some clarification from the vendors.
Injector Dipoles (DU/DV)
o  The DULY finished working on the revisions to the drawings of the Small Injector Dipoles (GV) and started
    the same process on the Large Injector Dipoles (GU).
Arc Dipoles (GY, GX, GQ)
o  AES completed initial design of the Reverse Bend (GQ) with all features being defined and detailed, achieving
    the same status as the Bend Dipole (GX) and the 180 Degree Bend (GY)
o  In magnetic modeling, they revisited the 180 Dipole (GY) achieving David Douglas’ specifications.  They
    adjusted the bulk field and current to match the GX by adjusting the Purcell gap and the vacuum chamber gap.
    They adjusted the end face position and the angle of the path length coil slot to bring the field integrals
    throughout the good field region  into 180 degrees of effective length. David Douglas checked their results and
    approved the model.  They continued by working on the final configuration of the Reverse Bend Dipole (GQ.
    At month’s end they almost achieved David Douglas’ specifications.
3 inch quad (QX)
o  We eliminated 1/3 of the remaining higher order multipoles due the pole tips’ end field roll off by further
    chamfers in the pole ends of the prototype.  We reflected this change into the drawings and the change was
    agreed to by the core vendor.
o  The specification for assembly and the assembly drawing were signed and placed in the procurement cycle.
o Fabrication work continues on the first article core.
o The first article coil set passed inspection at Magnet Enterprises International.
Trim Quad (QT)
o  All drawings were completed and signed.  The Statement of Work for the procurement cycle went through
    two cycles of review and is in final polishing.
Sextupole (SX)
o  Robin Wines has not been able to continue with magnetic modeling over the last reporting period because of
    additional octupole task administration and work on the  and work on the assembly specification for the QX
Octupole (OT)
o  DULY Research was able to create a magnetic model of the octupole that matched the required field integral
    profile to within 2%.  The model used recycled corrector dipole coils with a pole shaped to the 2 dimensional
    octupole shape with truncated ends, placed on the coil bundle like a mushroom cap.  The coils are from the
    CEBAF machine. We will need an upgrade in the required power supply from our standard trim supply to the
    20 A, 50 V supply required for the Trim Quad. At month’s end DULY is attempting to find out what
    adjustments will bring the magnet to the 1 % required by the specifications. They will look at shims on the pole
    tip edges, rounding the pole ends and field clamps.
Beam Line and Vacuum
o The drawings for the girders and stands for the return leg were nearly completed.
o Work continued on the drawing set for the girders between Cryomodules.
o Work started on the layout of the injection and recombination area.
o  Work continued on the Interface Control Document for the task definition for the Arc and Optical Chicane
    chambers.  The work concentrated on the specialty chambers through which the optical beam has to traverse.
    Better definition of the optical requirements lead to less drastic requirements on the specialty chambers through
    which the optical beam traverses.
o The Dipole Steel order was placed with Bethlehem Lukens Steel with a 10-week delivery.
o We generated the first pass at the paperwork for the CRADA for the collaboration between Jefferson Lab and
    STI Optronics to test out their compact 180 degree bend design on the FEL Upgrade machine.

WBS 10 (Wiggler):
The measurement apparatus for the wiggler is complete.  The 3 dimensional probe from Sentron arrived as well.
The apparatus and the probe are being calibrated and should be ready for wiggler measurements. Final welding
was started on the dispersion section vacuum chamber.  There is one machine step after that and the chamber will
be ready for installation in the dispersion section magnet for measurements.

Work on the wiggler magnet test stand concentrated on device calibration.  The test magnet originally planned for
use in probe calibration was found to be unacceptable so the BA magnet was used.

The Sentron 3-axis probe has been calibrated using an arc dipole(BA) magnet.  The probe shows no evidence of
a transverse Hall effect at 3 kG so we should be able to measure all three axes simultaneously.  The zero drift in
the probe, though within specifications, is higher than in data provided by Sentron so we are exploring ways of
reducing the drift.  The measurement assembly is calibrated and ready for installation.

The corrector coils are installed on the dispersion magnet.  The only work left on this magnet is to finish wiring up
the corrector coils to the junction blocks.  This magnet will be measured after the wiggler magnets.  The
dispersion section magnet vacuum chamber is done.  The wiggler vacuum chambers are ready for welding on the
side tubes.

WBS 11 (Optics):
The outcoupler mirror holder design has been refined sufficiently that it fits within our space constraints. This
fixturing is also consistent with the high reflector mounting.  The vertical motion design is also well along, with the
actuation, leadscrew, and pillow block defined.  Thus, we are close to being able to place orders for some of the
longer lead time components.

We've also determined that the vendor for the rotary feedthrough can provide us with a gear ratio that gives us
good resolution, and reasonably rapid translation.  The position-sensing portion of the mirror metrology system is
being tested; an engineer has been assigned to the team to assist in the design of some of it's hardware.

The purchase requisition for the new drive laser has been placed and the RFP was sent out this month.  Only one
vendor submitted a bid.  The price is far higher than our estimate, so we are working with the bidder to
understand their price discrepancy.  We are also revisiting alternate scenarios for building our own laser.

Set up optics to generate visible (525 nm) and ultraviolet (262.5 nm) light, then provide this light to users from
Aerospace Corp. (H. Helvajian and F. Livingston). Even with much improved sample mounting, we are
measuring the same conversion efficiencies determined last March (~ 40% IR - Vis, 20% Vis - UV).

We began calibrating the IR camera on the mirror test stand, so we can determine the losses of our mirrors.
We did measurements to determine the loss of one of our 6 um HR mirrors.  Preliminary analyses of the data sets
the loss below 300 ppm.

We measured the phase noise of the drive laser.

Analyzed epoxy tests, determining the bond thickness to be 175 microns of the epoxy we will use to affix mirrors
to the deformable mirror assembly.  Outgassing wasn't excessive; pumping overnight reduced this to below 1e-9

The FEL was operated for the last three weeks of the summer run for microfabrication studies (CWM), laser
ablation for carbon nanotube production (CWM/NASA/Penn State), UV processing in photosensitive glasses
(Aerospace Corp.), vibrational energy transfer in proteins (Princeton),and terahertz radiation generation (JLab,

Measurements of the higher-order mode power in the electron beam and its dependence on beam parameters
were made on Aug. 13-14.  A complete set of data was obtained for analysis for our 10 kW
upgrade and subsequent machine evolution.

The THz radiation experiments were made with visiting scientists from BNL and LBNL.  Larry Carr
(Brookhaven National Lab), Michael Martin and Wayne McKinney (Lawrence Berkeley National Lab), joined
G. Neil, G. Williams, M. Shinn and K. Jordan to set up a rapid-scan Michelson interferometer to observe
multiparticle coherent synchrotron radiation in the THz (far-IR) spectral region.  They observed far-IR coherent
synchrotron radiation whose intensity varied as the charge per bunch squared.  They measured its spectral
content, and also the absolute power.  The effects of bunch length were also measured.  In this spectral region
such a source provides almost 1watt/cm-1 of average power, which is many orders of magnitude higher than any
other source to date and probably enough to drive non-linear processes in a new regime.

This work is important to the 3 laboratories in two respects.  It links to the many projects involving accelerator-
produced IR and also sheds light on the utility of Energy Recovered Linac machines, mainly in addressing critical
stability questions.

The IR Demo was operated for two days to analyze phase noise in the drive laser and FEL output.