**MEMORANDUM**

**To:** Distribution

**From:** F. Dylla

**Subject:** FEL Upgrade Project Weekly Brief -- February 28 -- March 4,
2005

**Date:** March 4, 2005

**Highlights:**

After successfully lasing on two different broadband mirrors last Friday
at 2.8 microns we discovered a significant rf window leak in Zone 3
which prevented further beam running. The rf window was found to have a
crack when we removed the waveguide. We are in the process of warming up
the module and diagnosing the cause of this failure (the only time such
a failure has occurred in years of CEBAF or FEL operation while
operating with interlocks) and developing a plan to fix the leaking
windows. By Friday afternoon the module was still warming and outgassing
water which had collected inside. We will adopt a repair plan early next
week after close examination of the remaining\
windows\' vacuum and physical integrity. We thank the SRF team led by
Joe Preble and the Cryo Team led by Dana Arenius for their expeditious
and careful implementation of warm-up and pump-out procedures on the
Zone 3 module.\
\
We used this downtime from operations to catch-up on our back-log of
work on the optical systems and to begin the surveying in the vault for
the UV FEL chicane.\
\
The modifications to User Lab 4 were begun this week to accommodate the
installation of the Laser Microengineering Station currently being
completed by our collaborator, Aerospace Corp.\
\
We remind our readers that our annual FEL Users Meeting and Laser
Processing Consortium Workshop will be held next week at CEBAF Center on
March 9-10. The meeting agenda and registration is posted on our
website: www.jlab.org/intralab/calendar/archive05/FELusers-LPC/.

**Management:**

Meetings were held this week with the WBS managers for both the Navy IR
and AF UV projects to collect the cost-performance data for both
projects for the February monthly reports.\
\
We worked on our presentations and final arrangements for next week\'s
FEL User\'s meeting.

Gwyn Williams presented an invited talk at a special symposium at the
Pittsburgh Conference in Orlando, Florida, on high power THz light
generation.  This meeting, with over 1000 companies and 25,000
attendees, afforded an opportunity to engage with major security and
imaging companies as part of Jefferson Lab's technology transfer
mission.  Two major players present were Teraview and Smith's Detection,
who supply all the Ionscan explosive detection equipment at airports
worldwide and who have initiated a program to develop THz security
screening products.  Gwyn Williams also attended the science advisory
committee of the Center for Advanced Microstructures and Devices (CAMD)
as part of LSU in Baton Rouge.

**WBS 4 (Injector):**

The raw material for the segmented support tube fabrication for the
back-up electrode structure is in the machine shop. The segmented tube
will be polished, implanted with the field emission suppression coating
being developed jointly with the College of William & Mary, and finally
assembled to support the ball cathode in our second gun assembly.\
\
We have been working on the design of a new way to illuminate the
cathode in the 100 mA injector. Due to the required short drift between
the gun and the 100 mA cryo unit, there is not enough space to mount a
lightbox similar to the one currently used in the IR Upgrade Injector.
Mounting the lightbox downstream of the cryo unit will make alignment
very difficult. As an alternative, we have decided to use the anode
plate as a mirror. Input from Michelle Shinn and Steve Benson has
provided initial guidelines for the material and optical coating. The
design modifications to the gun chamber for this purpose are under way.\
\
We continue to make progress in setting up our lab in ARC including a
clean area for the gun final assembly.\
\
We started interactions with the JLab engineering team to look at
modifications of the gun stand for proper matching to the 100 mA cryo
unit. We are interacting as well with AES to exchange modeling
information and verifying that the physical dimensions of the
gun-cryounit assembly are in accordance with design specs.

**WBS 5 (SRF):**

-   QA Visual and CMM tasks have begun on the four 750 MHz fundamental
    cavities for the 100 mA injector CU along with preliminary tooling
    design.

-   Coordination with the FEL gun design personnel has highlighted a
    concern that may result in changing the cryounit isolation valves to
    an all metal sealing design.

-   A meeting has been setup with the JLab CASA group members this week
    to clarify the operational beam parameters of the machine in order
    to converge on a design solution for the HOM filters and beam line
    bellows.

-   Work has started on updating the overall machine component layout
    drawing which will also include component interface details.

**WBS 8 (Instrumentation):**

Efforts were designated this week to assist the SRF crew with the
cryomodule problems.  Each of the three RF Zones was powered down for
wave guide removal and inspection for the SRF group.  Zones 2 & 4 were
checked for moisture consistent with that seen in Zone 3 and all 8 of
the wave guide elbows entering into the zone 3 cryomodule were removed
for further window inspection.  Shorting plates were installed on all 8
of the wave guides in Zone 3 for safety purposes.\
    Progress continues on the DSP project for the Cool Down Temperature
Diode (CTD) PCBs.  Testing of the entire system is occurring as well as
individual test of the various sub components.  Several issues were
discovered throughout the system that still need further investigation
for appropriate solutions.  With Al Grippo\'s help timing issues with
the DSP were altered to provide useful test data to get a better
understanding of the functionality.  Documentation of all tests,
procedures, results, and ideas is underway so an accurate record of
where we have been and what direction we are heading will be readily
available.  Plans to carefully examine the code of the CTD PCBs to find
any hang-ups or glitches are the next step of the project.  Working to
finish up the epics2devlore project.  The only thing left to sort out is
http request management.  There is a max of 1024 bytes that can be sent
in one request.  This is a problem in that the requests that need to be
sent can be as much  as 10 times that size.\
    We were fortunate this week to be able to have some of the group
participate in the three day Mathematica training provided by Wolfram
Research. Although being able to use Mathematica is reason enough for
attending, we are considering how difficult it would be to implement the
product in the future as a part of our control systems. Mathematica
would be the heart of a machine model server which would open up many
possibilities in automating FEL operational tune-up processes. As from
any well taught class, we now have a much clearer understanding of what
can be done and how to do it and have the confidence in our ability to
do so. As a bit of proof-of-principle: - in the classroom - we were able
to import and analyze the latest FEL operations data being collected by
the Devlore system in real time (gun voltage and dump current versus
time). As the computational prowess of Mathematica not in question, our
concern is in how hard it will be to involve it in a real-time process.\
    The PC running our database application (devlore) and the website in
general (laser.jlab.org) was replaced this week with a much more
powerful machine and implemented on a new a subnet recently created by
the computer center to gather all JLAB machines that have accessible to
the outside world. This type of action is never painless, but - all in
all - it was accomplished without any real problems and interruptions in
service we minimal.\
  Several new Beam Viewer targets are in the process of phosphor
coating.  Four out of the five, coat then bake, iterations have been
completed and the fifth will occur over the weekend.  The Laser Glass
for the Lab 4 hutch has been received and is being modified by the
machine shop to fit into place. The MPS Summation Chassis documentation
has been all together completed and signed off.  The RF-DC Linear
Converter PCBs are in the assembly process and testing will occur as
soon as completed PCBs are available.  Progress continues on the RF-DC
Carrier Board design and the enclosure for the RF-DC Linear Converter
PCBs.\
\
     Fabrication of the new video chassis is underway with testing
expected to begin within the next two weeks.  The Control Room
revitalization project is progressing nicely as all but four of the
table top monitors have been replaced with flat plasma displays.  The
User Lab monitoring panel is expected to be replaced within the next two
weeks as well.  Some of the monitors from the control room will be used
to assist local monitoring in the vault as that video system is upgraded
as well.\
    Construction continued for the Lab 3 experimental hutch, framing
should be finished this week. Paneling and door installation will begin
next week. Installation was completed for the requested hardware for the
conference room\'s computer/projector setup. Grounding of the cable
trays for all the User labs has begun. In order to meet the AC (120V and
208V) power requirements for the Optics and I&C group, Plant Services
will install a 75 kV transformer along with a 200A breaker panel. This
should get us through the UV upgrade with any satellite electronics that
we wish to have powered.

**WBS 9 (Beam Transport):**

***Sextupole (SF)***

• Fabrication is continuing at New England Techni-Coil. Steel is being
cut to size.  Conductor is still at the insulation coating manufacturer.

***Replacement Chicane Dipoles GW)***

•   Fabrication continues at New England Techni-Coil. The steel for two
of the four magnets is being machined to size.  Programs for the
machining centers are written.  The first coil is complete and being
pressed with the prepreg insulation tape partially set in an oven before
having the ground wrap applied before final potting.  The sheet material
for the Purcell Gap on the pole tips was received.

### UV Line 

•  The signal generator to allow us to cycle the QX quads through a
hysteresis loop at Magnet Test is one day overdue and the magnet is on
the test stand awaiting powering.

•    Tim Whitlatch set up his vacuum modeling program to model the
regions around the Optics Cans.

•   With regard to our plan to regain our schedule slip   

•   The ME Group has three designers working on stands and girders and
Butch Dillon Townes has finished his schedule.

•   Some NASA design engineers are being brought in for interviews.

•   DULY Research has a converging RADIA model, with the proper mesh, of
the original SC Sextupole that duplicates the original test values.  It
exhibits several parts in 1000 field error at the 1.9 mm.  They will now
extend the poles inward to increase the field integral and see if the
existing pole profile increases or decreases the field integral quality.
(The original profile didn't meet field integral specification -- so the
quality could go either way.)

•   The faster PC workstations are installed and running with initial
reaction from at least one designer: "design speed is improved".

•   We placed a contract with Advanced Energy Systems to design the
vacuum chamber and stands for the GW Chicane.

•  Design of the upstream and downstream corner chambers (now being done
as a pair) was complete. Before signature, we are waiting for the vacuum
analysis to see if a baking requirement may force us to make the
chambers less high to make room for thermal insulation at the pole
tips.  Dave Douglas is considering the effect of reduced height chamber,
if it is necessary.

### UV Wiggler Progress 

•  The stay-out zone drawing was signed.  Steve Gottschalk of STI
Optronics, the original maker of the wiggler says that we will be able
to shave the brass brackets on the wiggler that hold down the poles so
that we can use the 10 mm Chamber for the 11 mm minimum gap.  We
prepared the Chamber Concept drawing to transmit to Argonne National Lab
for a quote on design and fabrication.  The Wiggler Jaw Drawing is in
preparation.

**WBS 11 (Optics):**

***FEL mirrors:\
***After press time last week, we lased on each of two broadband HR
mirrors. One has far less aberration than the other, and we
qualitatively saw better performance with it. Once we are operating, we
will obtain quantitative data. We used this week to work on the bonding
of mirrors to their deformers (which make a deformable mirror assembly
(DMA)). The results were unexpected, and suggest the deformer has a
strong influence on the aberration, so we are quickly returning to a
more fundamental study, where the mirrors are bonded to metal disks.
Meanwhile, we have begun metallization tests on silicon mirrors, in
preparation for making the second generation DMA. In this design, the
unfigured substrate is bonded to the deformer, then sent as an assembly
to be figured and polished. Conceptual designs were prepared and sent to
several optics vendors for comment. We received the first 3 (of 6 total)
3\" dia sapphire substrates, and they are going through metrology.\
***Other activities:\
***This week we resumed work on the more final version of the optical
transport system. This system is more flexible in terms of handling very
high (+ 10 kW) IR output than the OTS Lite version presently installed.
We received the first half of the new collimator (dubbed \"collimator
can 1\") and began working on the turning mirror cassettes, with the
goal to determine the correct length of the wiring and water cooling
utilities. We did a series of measurements on beam quality and beam
position (drift and jitter) stability in User Lab 1, using the alignment
HeNe. Data analyses still need to be done, but the long term drift
appears to be less than 2.5 mm, and the jitter is in the 10s of microns.
We received more windowed valves, and the 4\" fast valves arrived. We
added more pumping speed to the existing OTS with the addition of
another ion pump, located in the OCR. We assisted I&C by providing our
vacuum oven.\
***UV FEL\
***We surveyed the literature (as well as emailed colleagues) on
synchrotron-based UV FELs to see what pressures are considered
appropriate to minimize the amount of carbon (from UV-cracking of
hydrocarbons) that would deposit on the mirrors. The specification for
ELETTRA (Trieste, Italy) is the partial pressure from light hydrocarbons
is 10e-11 mbar, somewhat more stringent than our design spec. Another
vendor of bakeout jackets has been found, and we are discussing our
requirements with them. The position sensing transducers appear to have
the resolution and range we require, now we need to check their vacuum
performance. An outgassing rate test setup is coming together to do just
that.

**Terahertz:**

Meetings took place with several vendors regarding optics, spectroscopy,
imaging and vacuum equipment for the laboratory.  Several applications
have been received for the postdoctoral position.