# MEMORANDUM 

**To:** Distribution

**From:** F. Dylla

**Subject:** FEL Upgrade Project Weekly Brief -- October 27-31, 2003

**Date:** October 31, 2003

**Highlights:**

We are holding to our schedule for re-starting FEL commissioning
operations next week. The key task of installing the final version of
the pi-bend magnet (GY) in first arc was accomplished this week. 
Alignment, vacuum, water cooling, and power hook-ups are proceeding
today through Monday. Significant other accomplishments this week
include: (1)  re-certification of Personal Safety System (PSS) which is
required for machine operations was done on Thursday; and (2) we had
first RF power onto the linac and injector modules.  Next week after
completion of the GY installation we will devote most of machine
operations to RF conditioning of the linac modules.

We note that start-up of the CEBAF linac after the storm hiatus has gone
well. We thank the efforts of the SRF, EES, Software and Cryo teams for
bringing these systems back on line.

**Management:**

F. Dylla attended the FEL Technical Working Group (TAWG) meeting
organized this week (Oct. 27-28) in Albuquerque to review the proposed
FY04-05 FEL program activities for the Navy and the JTO.  Our Jefferson
Lab presentation described work in three task areas: (1) completion of
commissioning and characterization of the 10 kW FEL, in its present
configuration and after installation of the 3rd cryomodule and new 1
micron wiggler; (2) further development and testing of the JLab/AES 100
mA DC injector; and (3) scaling studies in SRF  linac configurations for
development of higher power (100kW+) FEL devices.  Presentations at this
meeting were also given by NPS, LANL, NRL, ANL, BNL, AES, Inc. and SAIC,
Inc. The Navy program management has promised to distribute a summary of
the meetings findings and recommendations as soon as possible to keep
the FY04 program on track.\
\
Preparations continued this week for next week\'s visit (Nov.3rd) by Dr.
Ray Orbach, Director of DOE\'s Office of Science on the occasion of the
Lab\'s annual \"Institutional Planning\" review.\
The strong support of the Navy and AFRL for the Lab\'s FEL development
program will be highlighted during a portion of the review.

Gwyn Williams presented an invited talk on THz light generation at a THz
session at the meeting of the IEEE Lasers and Electro-Optics Society
meeting (LEOS-2003) in Tucson.  The talk was well attended and gave an
opportunity for interaction with potential users of our high power
source.

**WBS 4 (Injector):**

The cathode QE is about 0.6%. This should be sufficient to start FEL set
up operations.

The HV test stand was baked to 150 C for about two days. This week,
Survey & Alignment crew set the gap between the test electrode and the
anode. Everything is ready to HV test the electrode with the field
emission suppression coating.

PARMELA simulations are being carried out for the UV FEL at 350kV, 60
pC.

**WBS 5 (SRF):**

*FEL3 Status:\
*Work is picking up on FEL3. Most of the technicians are back from CEBAF
recovery and a high level of activity is resuming on both FEL and SNS
modules. The cold mass MLI is now completed except for a few details at
the ends of the string. The thermal shield has been installed on the
string and the fit and clearances are being checked. Once this is
verified the shield plumbing and instrumentation will be installed. The
next step after the shield work is complete will be installation of the
space frame.

The FEL module has three new diodes on the HOM can as part of the
instrumentation package. This will help to verify models of the
temperature performance of the HOM can assembly.

**WBS 6 (RF):**

Operations - All RF systems and the Gun\'s HVPS were operated this week.
The PSS was re-certified for the entire machine. The nominal values for
the Cavity Waveguide Window Temperature (CWWT) were checked and adjusted
as necessary for all cold cavities.

INJ - The Injector RF was run at full operational gradients. The Bunch
Length Phase Modulator was upgraded, installed, and tested this week to
include any combination of the Injector cavities and Drive Laser.

Zones 2 & 4 - were run to 5 MV/m where beam line vacuum faults caused
trips. Cavity FL04-6 had a tuner motor fail. It was replaced and the
tuner now functions properly. These zones need more run time to cleanup
the vacuum faults. In Zone 4, new ceramic warm windows and in front of
the CWWT detectors, RF screens were installed.

**WBS 8 (Instrumentation):**

Testing of the AMS/Video Upgrade 32 X 32 crosspoint board (F0253)
prototype is proceeding well. The CAN bus interface works well with a
pre-programmed processor, but to re-program the device \"in-system\"
requires a different programming cable than the one we have.
Nonetheless, we have developed our CAN buss interface firmware on a
development platform and then transplanted the programmed processor onto
the crosspoint board prototype. With the first chassis fully finished we
are ready to begin measuring the analog performance characteristics of
the finished chassis from chassis input to chassis output. This will
include a complete crosstalk characterization. In parallel with the
testing of the prototype crosspoint chassis, a 32 channel, high density,
analog distribution amplifier board is being designed. This board will
be used to terminate the \"WIRE-OR\'ed\" outputs of both the video and
AMS systems. The board will be implemented in a chassis similar to the
crosspoint chassis. Currently, we are in the PCB lay-out stage of the
video amplifier design and its chassis is being constructed in Lab 5.\
   

A calorimeter has been built to measure the THz power emitted from the
electron beam as it makes the 5F01 bend. This is mounted on a pneumatic
cylinder and 6\" cross in front of the downstream optical cavity. Many
thanks to the JLab machine shop for a quick turn around on the parts. It
is fitted up with 2 different heaters, 2 RTD thermometers, and 2
temperature diodes. It is fully assembled, tested, and installed. Thanks
to the Optics Group for assistance in leak checking and doing a good
bake prior to installation.

![](media/image1.jpeg){width="2.9229166666666666in"
height="1.988888888888889in"}

The EES fab group has finished assembling the eight VME interface
modules that are used on the programmable timer boards. The interface
boards need to be tested in an IOC, but after which we are ready to
implement timer boards as needed now. These will provide agile timing
references for the many devices we use to characterize both the electron
beam as well as the drive laser and the FEL itself.\
   

GC Magnet Control boards have all been completed.  The power supplies
for MGC5F01 and 5F03 have been completed, installed and are ready for
operation. The third chassis is awaiting final test and the fourth
should be ready for installation by Tuesday. Each chassis is a floating
supply, two isolated channels per QT Panofsky Quadrupole magnet to
adjust fields to give a vertical  kick. These power supplies ride on the
primary power supply of the quad which is a four quadrant 75 volt/ 20
amp supply. DC power for the 1st Arc GY dipole has been completed.
Installation of the GY shunt, shunt  resistor and thermal interlocks are
in progress with checkout beginning early next week.\
   

Rigorous testing has been performed on the Linux frame grabber\'s
center-of-mass measurement. Some calculations produced readbacks that
are inconsistent. But the problem is being narrowed down. A current
problem with UDP errors associated with IOCFELT2 is being looked into.
It was discussed with Joan Sage to insure that the frame grabber
software was not causing such problems. Tests have been done eliminating
situations from the list of potential sources.\
   

The new Laser Personnel Safety System (LPSS) machine has been installed.
This contains the database and access control for the user labs laser
safety systems. The OCR and labs 1, 2, and 6 are operational. There were
problems with the reader at lab 3. The source has not been determined at
this point but it is not currently certified for laser operations so
there is no adverse impact. A key feature of the new system is an
operational keyboard. The new machine is placed in the CR racks with the
old one being stored in the OCR as a backup system. All cables have been
relabeled for their updated COM port assignments. The COM ports on the
machine have been labeled accordingly.\
   

Drawings for the microvideo camera boxes and the Charge Dump Current
Monitor Buffer Driver are in the final stages.  System drawings for the
Charge/Dump Current Monitoring System are also in progress. 

**WBS 9 (Transport):**

[Arc 180 Degree Dipoles (GY)]{.underline}

• For the second GY, we instituted our fix to keep the Purcell Gap
lamination material in place for upgrade level momenta (Max. is 210
MeV/c and we are at 90 MeV/c now). Don Bullard and Mike McCrea from the
JLab Machine Shop worked Saturday and Sunday to apply the compressed
o-ring stock to the Purcell Gap lamination material. With the same
operation, they installed the beam chamber. The magnet was rigged into
the FEL vault and into the first arc on Tuesday. The stands (which had
to be removed in order to roll the magnet into place) were repositioned
and grouted. We aligned today. Hook up of power leads, attaching the
vacuum chamber, installing the cooling water connections, shunt system
and the synchrotron light diagnostic periscope as well as final
alignment are all activities planned for over the weekend and early next
week. The shield blocks were replaced against the overhead door of the
vault.

![](media/image2.wmf){width="3.875in" height="2.848611111111111in"}

"The GY just fits."

• There are no signs of delamination of the Purcell Gap lamination
material in the GY of the second arc. It is only run up to 60 % of
maximum current with operation at our low momenta and therefore we are
not worried about delamination. When we go to higher momenta, we have
the material on hand and a rigging plan for popping the top of this
magnet to insert the compressed o-ring stock.

SF Sextupoles

• Mel Gonzales of the electrical CAD group continues making good
progress in revising the drawings of the SF Sextupole design. The
specification to match the drawing package is nearly complete.

**WBS 11 (Optics):**

This week\'s work on the optical cavity continued measurements of the
active feedback system.  More insertable optical diagnostics (e.g., a
high power optical beam dump) were installed and checked out.  Thanks to
the I&C group for their help.  We continued to work on improvements to
the optical cavity that will be ready when we open the vacuum vessels to
install new mirrors.  One improvement is cooling line fixtures to better
secure them, and they are being cleaned for UHV use.  Another is
the new outcoupler mirror holder, it was cleaned and brazed, and is at
the Machine Shop to have the hose connections attached.  The first
article looks so good that the second ring is being built now.  We
assisted I&C with parts for the calorimeter that will be placed before
the outcoupler mirror and used to measure power (especially in the IR
and far-IR) radiated towards the mirror.  We held several design
meetings to prepare for adding new penetrations for the UV optical
transport, and an EUV (from coherent harmonics) line into User Lab 1. 
In the process, we have a new scheme for mounting the turning mirror
cassettes in the user labs.  

The ultrafast laser system was moved to the vault where it will be used
in a pump-probe arrangement to better determine the injected bunch
length.  The associated optical delay line was installed and aligned
earlier this week.  The periscope that routes THZ light from the port on
the optical chicane to the FTIR was reinstalled and aligned.  It has a
simple shroud around it so the path can be purged with dry nitrogen. 
This should remove some of the spectral artifacts due to water
absorption.

New fixturing for mounting cavity optics in the mirror test stand were
used this week, and are a big improvement over the simpler (and less
rigid) mounts we\'d been using.  Fixtures that will be used for laser
calorimetry were also tested and work well.

**Terahertz Project:**

The drawings for M1 and the specifications are complete and ready for an
initial bid solicitation.  The mirror actuators for M1 and M2 and the
beamline vacuum components, pumps gauges and valves have been
identified.  We are still awaiting bids on several beamline hardware
components.

**Technology Transfer:**

Five different FEL/Tech Transfer activity reports for FY03 were
completed and submitted this week:

> \- 3 to Jim Murphy (JLab Office of Technical Performance) for contract
> obligations,
>
> \- One to TPWG (Bob Hamilton in Oak Ridge) for DOE\'s master dBase for
> Tech Transfer,
>
> \- One to DOE\'s SBIR/STTR database of expertise at JLab.