# MEMORANDUM 

**To:** Distribution

**From:** F. Dylla

**Subject:** FEL Upgrade Project Weekly Brief - September 19-23, 2005

**Date:** September 23, 2005

**Highlights:**

This week we continued our installation maintenance activities. Progress
this week included:

> \- completion of the installation and check-out of the controls for
> the new permanent magnet infrared wiggler
>
> \- completion and grouting of all the support stands for the UV
> chicane beam transport hardware
>
> \- installation of two of the THz chicane dipole magnets (GWs) in the
> UV line
>
> \- installation of \~40% of the power and control cabling for the UV
> chicane
>
> \- completion of helium processing on the first linac cryomodule

**Management:**

George Neil served as conference chair for the 2005 International
Conference on IR and Millimeter Waves held this week in Williamsburg and
locally hosted by Jefferson Lab. Much of the conference focused on THz
applications and we hosted 200 of the conference attendees for a tour of
the FEL Facility on Sept. 22.

Also on Sept. 22, we hosted a visit by Virginia's Senate Appropriation
Committee. We showed our appreciation for the Commonwealth's
contributions to Jefferson Lab which help fund FEL user collaborations.

We continued our monitoring of end of fiscal year expenditures and
planning for a smooth start of next year's activities. We acknowledge
the considerable help of our ONR and AFRL program managers and DOE
contracting officer for their able assistance with this annual
transition.

**WBS 3 (Beam Physics):**

We generated a few layouts using the injector to drive a THz source
based on the W80 IR wiggler. This looks reasonable using components
similar to those already in use.

We completed analysis of difference orbit data. It appears that numerous
BPMs (including nearly all downstream of the wiggler) were reading
unreliably. Several quads act as though they were far from their nominal
setpoints. These data are helping generate input for our maintenance
list during this shut-down. Sample orbits -  before and after correction
for quad focusing errors - are given below:

1F01H before correction

![](media/image1.png){width="6.497222222222222in"
height="1.3506944444444444in"}

1F01H after correction

![](media/image2.png){width="6.4944444444444445in"
height="1.3541666666666667in"}

F01V before correction

![](media/image3.png){width="6.4944444444444445in"
height="1.3465277777777778in"}

IF01V after correction

![](media/image4.png){width="6.496527777777778in" height="1.35625in"}

The quad excitations influence what you think the beam envelopes are:

Uncorrected:

![](media/image5.png){width="6.491666666666666in"
height="1.3402777777777777in"}

and corrected

![](media/image6.png){width="6.491666666666666in"
height="1.3402777777777777in"}

**WBS 4 (Injector):**

This week Don Bullard completed 1-micron finish polishing of the third
and last electrode tube segment for the new gun assembly which will be
used in the Injector Test Stand. Today the second tube segment coated in
the W&M\'s plasma chamber last week was removed and replaced with the
third tube for processing. We expect to fully coat this tube by the end
of next week.

The hat flange for the new gun assembly has been welded and we keep
making progress collecting all the components needed for the gun
assembly.

We supported multislit and viewers assembly work.

**WBS 5 (SRF):**

This week helium processing on the FEL02 module (the first linac module)
was completed

during second shift runs this week by the SRF team. 30k thermal cycles
were planned for today for this module and the cryounit so that these
units could be power tested next week. A plan was put together for a
complete thermal cycle on the FEL03 module starting next week, so that
this module can have a complete leak check, followed a cool-down and
helium processing. We have decided to keep this module in place for use
in then next quarter since the Renascence module delivery will be
delayed for additional testing.

Progress on the 100 mA injector cryounit included:

-   Preparation for VTA testing of the third harmonic cavity have begun
    following the decision, not to mechanically alter the cavity
    geometry in order to affect the coupling and to use this cavity "as
    is". Calculations show the FPC can be terminated with a niobium
    plate without any concerns for standing waves or resonant
    conditions.

-   Tooling design for cavity testing and handling is progressing to
    meet schedule for helium vessel welding in October. The cavities
    will be tested in the VTA after helium vessel welding is complete.

-   Preparations have begun to plan the logistics to rf process the
    fundamental power couplers at SNS after they have been received by
    JLab for inspection in November.

-   The final cost and performance analysis is being completed for the
    HOM coupler feedthrough design. Fabrication is expected to begin in
    early October.

**WBS 8 (Instrumentation):**

The effort to have 8 sets of 4-Channel FEL BPM Electronics ready for
when operations resume is still a major priority.  The few remaining
parts that were ordered have all been received and accounted for.  The
final changes to the PCB have been documented and a quote for boards
will go out as soon as the Gerber data is ready.  Other details that are
required for the system to be operational are in planning and progress,
such as the IP Address requests, power supplies, and cable
installations.

    The Sextapole Reversing Switch control board prototype has been
completed.  The board is currently being fitted up with the rest of the
components in the enclosure to get a mechanical layout.  Once a final
mechanical layout is completed the board will be tested with the rest of
the electronics.  The bus work for the layout will be documented so the
parts can be manufactured properly so every switch will be consistent. 
The 4-Ch RTD board for the DSP Crate has been ordered and the
documentation has been signed off.  The front panel documentation for
these boards has also been completed and signed off. 

    All Beam viewer video and signal cables for the UV upgrade were
installed and routed to their destinations this week. Bench checkout of
our camera spares has begun so we can replace radiation damaged cameras
in the vault before hot checkout begins. A data sheet for viewer camera
maintenance was begun this week also. This Excel spread sheet will be
put in devlore as an active database of all the viewer cameras on one
sheet. It will be used as a hot checkout checklist and will serve as a
template for other systems. It can also be used as a guide for newer
employees to show some of the basic steps involved with setting up the
beam viewer cameras. Installation of signal and power cables for the
rest of the Vacuum system on the UV (Piranni gauges, Cold Cathode
Gauges, gate valves) has also begun.

    We worked in conjunction with STI Optronics on the installation and
commissioning of the new IR Wiggler. It has been successfully tested,
the EPICS wiggler control screens are all operational.  Currently in
the process of getting STI\'s software setup on an FEL PC, and planning
the full migration into the FEL\'s controls.

    We are in the process of selecting the right RF coupler to use on
the multipass BPM signals. Our intent is to couple -10dB off the
normal system to be used in a new BPM system that will be able to
separate out the first and second pass beams. The primary concern right
now is to select a coupler that will not reflect any higher harmonics
back into the existing system. Currently, we have characterized 4
coupler models and have made the S11 (input signal refection), S21 (both
primary throughput and the coupled throughput). We will most likely
order what we need by COB today.

    The generic EPICS signal analyzer tool is close to its finished
form. We are working out some final bugs in how the statistical analysis
of the 60 point ring buffer is done, but this will be finished shortly.
The primary motive of this tool is to improve the reliability of the
BPM position readbacks.

    We spent some time debugging the machine performance archiving tools
for Devlore. The RF fault logger has been working great; however, the
timed updates data has not been working as designed. This should be
solved now.

**WBS 9 (Beam Transport):**

# *Sextupole (SF)*

•     The first unit was received and is being mounted on the Test
Stand.

• At New England Techni-Coil, the remaining ten units will be shipped
next week.

**Replacement Chicane Dipoles (GW)**

• The remaining two units will be shipped next week.

# *UV Line*

• STI didn't qualify its method of measuring and didn't check the probe
tip motion range in X and in Y using optical tooling techniques. While
they were out a Jlab for Wiggler commissioning they had a tutorial on
refinement of their optical technique from the alignment Group.

• Meanwhile, quads are not tested and girder assembly remains on hold.

• All stands are grouted and two GW dipoles are installed.

• The orientation of the BPM strip lines in a BPM further held signing
the Regional Assembly of the 8Fsub4. That issue has now been cleared by
changing spool lengths and slight repositioning. The two remaining
signatures will be added.

• The NEG Pump cartridge holder design is on hold until a designer is
available.

# *UV Wiggler Progress*

•     No progress on the new Wiggler vacuum chamber.

# *IR PM Wiggler Vacuum Chamber Progress*

•     The support structures for the OCMMs and chamber were delivered
and installed. The chamber crown was removed by skillful bending by
Willy the welder and the chamber tubes were cut to accept the flanges
and all parts were sent for cleaning.

# *Down period issues for the IR portion of the FEL*

•     SF Sextupole installation in the second arc is a must.

• We wound new trim coils for the QT/GC combined function magnets and
improved the field quality to 4 parts per 1000. We are planning a full
series of measurements early next week with a power supply system the
fully mimics the final magnet usage.

• The replacement paddles for the Multislit were finished and its shield
repaired. Re-assembly will take place next week.

• The shop is working on a Gauss meter probe fixture that will be able
to be inserted between all four pole tip gaps of all the quads of the
machine to aid in investigating why some quads appear to have gross
field errors.

**WBS 10 (Wiggler):**

Staff from STI Optronics came out this week to set up the new
W55 permanent magnet wiggler, set the travel limits on the jaws,
and deliver all remaining documentation.  We had a problem with a
failed uninterruptible power supply (UPS) and some network problems
that slowed things down, but we were finally able to get the
wiggler working under both Visual Basic and EPICS.  All the limits
(there are several layers of machine protection) were set.  The supports
for the vacuum chamber were then installed.  We are now trying to get
the Visual Basic program working on one of our computers and cleaning
up a few punch list items for the wiggler controls.  Valuable
lessons were learned during this exercise that should make the UV
wiggler installation go much smoother.\
The vacuum chamber should be done this weekend and will be cleaned and
leak-checked next week.  One this is done, it will be installed and
aligned along with the 6-way crosses that hold the OCCMS mirrors.  At
that point the wiggler viewers will be installed.

**WBS 11 (Optics):**

***FEL Mirrors***:

We inspected, bonded and brazed what seemed like a myriad of optics this
week in anticipation of replacing most of the FEL cavity optics next
week. The stiffener ring we bonded to the 3" 1.6um DMA appeared to do
little to improve the astigmatism, however, increasing the cooling water
temperature slightly did the trick. A 4" BB DMA was bonded this week and
will be inspected on Monday after the adhesive cures. The 4" BB OC was
brazed twice this week, the second time to fill voids in the In/Ag braze
alloy. An inspection of the optic showed that we had introduced too much
astigmatism. A final re-melt is scheduled for today with an inspection
to follow on Monday.

***Other Activities***

Work on the drive laser went well regaining spec. performance. The leak
in the primary cooling system for the drive laser was tracked down to a
faulty seal in the pump housing. Welding began on the optic transport
line to allow us to terminate the FEL light in Lab 6. Group members
attended two conferences week, the DEPS Ultrashort pulse meeting in
Boulder and the IRMMW-THz conference in Williamsburg.

**Terahertz:**

This week we worked on the M1 and M3 remote manipulators.  Taking
advantage of the IRMMW conference, we met with several vendors and
established specifications for detectors, polarizers and lenses for the
THz laboratory.  Preliminary discussions were also held concerning THz
cameras.