# MEMORANDUM 

**To:** Distribution

**From:** F. Dylla

**Subject:** FEL Upgrade Project Weekly Brief --August 11-15, 2003

**Date:** August 15, 2003

**Highlights:**

As we left our audience with last week\'s report on the FEL Upgrade\'s
journey to 10 kW, we had just successfully energy recovered 80 MeV
electron beam while lasing at low duty cycle (2 Hz set- up mode). By
Tuesday of this week we extended the macropulse length to 1.5ms with
relatively clean transport of the recovered beam. On Wednesday we took a
half day break in operations for an OSHA inspection and took advantage
of this break to recesiate the cathode, install the high power optical
dump/ power meter that will measure the FEL output, and prepare the
machine for calibration and certification of the beamloss monitor (BLM)
system for cw operation. Yesterday and today we worked through the
laborious process of calibrating all the BLMs from the injector through
the reinjection point by steering the beam off-axis at each BLM
location.  The photogun recesiation was successful and the optical dump
is ready for operation. We are ready for ramping up the duty cycle
towards cw operation which began late this afternoon at press time.

We are pleased to report on the successful completion of the FEL third
cryomodule cavity string assembly which now moves onto the final step of
cryostat assembly. We thank the SRF cavity team under the direction of
John Mammosser for their efforts.

**Management:**

We received a fast turn-around from John Albertine on the draft MOA
submitted last Friday for FY04 ONR funded FEL Upgrade operational
activities. The requested edits are minor and a revised draft will be
submitted as soon as possible.\
\
From Tuesday through today we had an OSHA team on site for a complete
inspection of\
Jefferson Lab.  This inspection provides information to DOE for the cost
of moving the DOE Labs from DOE oversight to OSHA for safety compliance.
The OSHA team spent Wednesday morning in the FEL Facility. We are proud
of the results from both of the Lab and specifically for the FEL. Only 7
findings were noted in the FEL and all of the items can be ameliorated
with minor cost or impact.\
\
 On Tuesday and Wednesday we were visited by a three person team (Ron
Reid, Steve Bennett, and Khalid Fayz) from the Daresbury Lab that has
the responsibility for the design and construction of a photogun for the
4GLS prototype light source. We provided them with drawings for the FEL
dc photogun under the auspices of our current agreement to collaborate
on technology of joint interest with regard to energy recovered linac
light sources. The 4GLS project currently has the wiggler from our 1 kW
IR FEL Demo project on loan for the duration of their prototype project.
Eventually, the 4GLS project intends to design and build a 100 mA gun
with specifications similar to our current joint project with AES, Inc.
on a next generation FEL injector.\
\
A white paper requested by the Transportation Security Working Group was
submitted by Passport Systems, Inc. on Aug. 12th concerning the use of
the FEL injector beam for testing a prototype x-ray flourescence
detector for cargo security (see last week\'s report for details).\
\
JTO and THz project monthly reports for July were prepared and sent to
the DOE, JTO and US Army NVL program offices.

With the Director's Office and CFO, we prepared our presentation for
next week's (Aug.21) defense of our state budget appropriation
(FY05-06). The Commonwealth provides essential funding for supporting
FEL user operations.

**WBS 4 (Injector):**

The photocathode QE was increased from 0.8% to 3.7% by re-cesiation.
Afterwards the photocathode was high voltage processed to 360 kV in the
conditioning resistor configuration. No field emission was observed on
the ceramic viewer. Some current activity was observed around 350 kV,
but cleared off after a few minutes and was stable at 360 kV for about
30 min. The conditioning resistor was then shorted out with the running
resistor to continue normal beam operations.

**WBS 5 (SRF):**

The good news is that the FEL third cryomodule cavity string is complete
and under vacuum. The string is now pumping on the ion pump and was
transferred to the cryomodule assembly area on Thursday. There was a
slight delay waiting for the assembly rail to be available. The string
completion is the result of a lot of hard work by the cavity production
group under John Mammosser. The torch has now been passed to Joe
Preble\'s cryomodule assembly group to work their magic.

![](media/image1.jpeg){width="3.598611111111111in"
height="2.1486111111111112in"}

**WBS 8 (Instrumentation):**

The 3kW path length corrector (MGG5F02)  power supply was installed in
the rack (FL05B06) communications installed, and software uploaded. The
temporary power supply worked, but had poor resolution and only manual
control.  Video, beam viewer and stepper motor signal and power cables
were pulled in to the High Reflector and Out Coupler OCMMS.  Progress
was made on the GC power supplies.  Parts were order and a preliminary
design is in progress for two channels to be in one box.

Additional beam viewer cables were pulled into place for the diagnostic
and optical beam dump insertable mirrors.   The HR Analog Chassis and OC
Analog Chassis were both returned from EECAD with completed and signed
documentation.  These two chassis will be installed in their respective
locations downstairs when the machine is open.  The HR & OC Buffer board
was installed in the HR & OC Analog Breakout Chassis in the control room
and the connections to the chassis were made to accommodate heater
control.  The HR thermocouples and heaters for the mirrors are hooked up
and in EPICS.  The other signals will come with the two chassis being
installed downstairs.

The heater control and water flow interlock for the HR mirrors were
implemented into the system.  With this configuration the heaters can
not be turned on unless the water flow is made up.  The design process
was started for the EPICS interface and local control of these heaters.

The Machine shop returned the chimney mount for the silicon viewers, and
they returned parts for new testing chamber for crystal quartz. New
cameras are being assembled for the synchrotron light monitors, however,
we could only complete two full working cameras due to a lack or parts.
Additional parts for the cameras were ordered through the stockroom, and
will arrive in three days. 

The MPS Certification procedure is in the rough draft form as is the BLM
Checkout procedure.  An \"Equipment Specific Lockout/Tagout\"
instruction for the magnets with multiple power supplies is also in
routing for comments.

Thank's to all for your work preparing for this week's OSHA inspection.

**WBS 11 (Optics):**

This week began with further characterization of the cooling water
induced vibration.  Until we incorporate fast feedback on the cavity
optics, the easiest way to deal with it will be to lower the flow rate
and let the edge temperature of the optic rise another 1 deg C.  We
investigated a nonlinearity in the pitch motion of the 4\" OC (which
will be used for high average power) and determined it is most likely
due to an incorrect setting of the preload spring.  It will be set to
the correct value when we next open the vacuum vessel.  During the
machine maintenance/OSHA inspection period, we reinstalled the FTIR
spectrometer on the optical chicane THz viewport, added stiffening
panels to the OC OCMMS equipment stand, and installed an additional
chamber containing a commercially available power meter.  While testing
showed it capable of pumping into the 1E-7 Torr range, when moved
downstairs we found a leak had opened up.  We replaced the fittings and
the power meter Thursday evening, but had another leak, which was later
determined to be due to a crushed fitting.  In order to have a high
power beam dump during initial lasing, we switched to our back up plan,
which was to install the prototype 50 kW diagnostic beam dump.  Other
work which was done in concert with the I&C group and completed in time
for high average power lasing was (1) EPICS control of the vacuum valve
between the diagnostics and the optical cavity, (2) installation of a
flow interlock switch to the deformable mirror electronics.  We continue
our work with the Mechanical Engineering group on the UV optical
transport system and optical beam positioning system.

**Terahertz Project:**

A meeting was held at AES in Medford,NY with Vincent Christina to
discuss details of the mechanical layout of the THz optical transport
system. The first draft of a layout was completed this week.  This
formed part of the iterative process necessary to optimize mirrors and
vacuum chamber components.  The floor penetration location depended on
this and has now been defined.  The Nicolet Impact-400 Michelson
interferometer was placed in the vault and optically coupled to the THz
port for tests.