Highlights:
This week the FEL was operated for continuing
the spectroscopic work of G. Luepke for his investigations of the
H defects in Si. The team was able to improve
the wavelength and pointing stability of the FEL to improve his signal-to-noise
a factor 4-5 compared to his experimental run in November.
Management:
This week F. Dylla and C. Leemann had the pleasure of meeting the Chief of Naval Research, Admiral Jay Cohen at the Feb. 5-6 meeting of the Virginia Research and Technology Commission in Richmond. During off line discussions Adm. Cohen expressed in his interest in the FEL program and his desire to visit the lab in the near future for a tour and briefing.
We submitted this week, jointly with VCU, a $3.75
M proposal to the Commonwealth Technology and Research Fund for recommissioning
the x-ray synchrotron donated by one of the FEL industrial partners.
Also three proposals went to NSF this week by
FEL users to support FEL user lab infrastructure.
WBS 3 (Beam Physics):
B. Yunn evolved an injector solution based on
the 500 keV Engwall gun, sporting very low emittance (~2;3.5 mm-mrad/16;32
pi deg-keV) at high charge state (~135;270 pC). This is adequate for the
UV driver and
likely will support JERBIL (D. Douglas's concept
for a 4th generation light source). Work continued on interfacing
the UV bypass, with most effort focussed on management of momentum
compaction while avoiding impressively strong trim quads.
WBS 4 (Injector):
Continued gun chamber design for the Upgrade gun.
Started planning for gun testing an the end of the 2001.
Gun HVPS - Resolved the differences with the
vendor concerning the multiplier stacks. There is just no other alternative
to 2 multiplier stacks and 1 monitor stack. This means the HVPS tank
will have to be
extended for the additional multiplier stack.
WBS 5 (SRF):
Two (2) cavities fabricated this month;
this makes four (4) complete (less groups).
First article helium vessels are undergoing
inspection and QA.
HOM component design completed and components
are being fabricated.
Stress test of the beamline flange completed
this week. Flange was deflected 50 mrad and remained
leak tight at 2K
WBS 6 (RF):
Zone 3 - No progress.
Zone 4 - The system was brought into RF ON for
cavity 1 this week. Work continues on the test software to complete
and
document the zone.
Injector RF - Ordered 2 autotransformers as backups for the existing 3 phase Variacs. PSC is still considering the cost and schedule impact of using autotransformers in the upgrade. Reliability and space requirements should improve.
WBS 8 (I&C):
The optical BPMs for the upstream optical table,
can 2, can 6 and End-of-the-Line Dump are experiencing some problems that
are elaborated on in the Optics section of this brief. The picomotor
cable in the drive laser clean room was also re-terminated to improve
reliability. Two new optical BPM detector assemblies were built and
tested and are available as well as new cables
for testing the BPM system. A test cable for the new “quad-detectors”
has been fabricated, as has a “break-out” cable to monitor and log RS232
“communications”. Two new local shutter control boxes for user labs
are complete and await testing. Also in progress is the construction of
power supply racks for each of the user labs. Drawings are in to EECAD
for GPIB System drawing and an update to the LSS User Interface Box in
the user labs.
WBS 9 (Transport):
Dipoles
Injector Dipoles (DU/DV)
o DULY Research continues to model the
Small Injector dipole. They are working the on the 3 D model
as well as the 2D details.
Optical Chicane Dipole (DW)
o We checked the drawing package and started
incorporating the information. We started on the
specifications for making
the magnet.
Arc Dipoles (GY, GX, GQ)
o AES started the layout the coil's leads,
incorporating the 4-in-hand winding and started re directing
the leads so the water connections
could be made while incorporating the bus bars and lead stabilization
comb.
o AES modeled the magnetics of the GY using
axisymmetric 2D model which makes provision for the
out-of-plane curvature of
the magnet. They found that the field is concentrated in the just
the inner return leg
such that the flatness of
the field warps to several times the allowed value within the nominal good
field width.
They will now work on a model
with increased width of return leg only to see if the flatness returns.
Their next line of action
is to increase the thickness of the pole plates.
o We worked out a way for the leads of the Path
Length Correctors to be mounted like the leads of the
IR Demo's injection dipoles.
Quadrupoles
QX (3.125" Quad)
o Measurement Probe: The vendor is performing
the final machining of the coil support plate coil slots.
o The procurement of steel was started.
o At a working session, we settled on a method
of machining fiducial surfaces on the quadrupole that satisfies
the ability to Wire Electric
Discharge Machine the pole tips, provides a mount for the magnets on the
test
stand, allows simple direct
mounting to single and double girders and provides for use of a bubble
level and
tooling balls during final
alignment. Sometimes committees actually work!
o Design Package: In parallel with his GW design
efforts, N. Vaughan is working on finalizing the QX drawings:
The drawing package is being modified
to incorporate the decisions of
the working session.
o Prototype Measurement: Effective length measurements
were made using a hall probe.
o Manufacturing philosophy: A meeting with Will
Oren, head of engineering technicians and shops resulted in a
decision to have separate
procurement of coils and a separate procurement of cores. Then, once
assembly
drawings are available, we
will probably procure assembly from the resulting vendors but keep open
the
option of assembling in-house.
Sextupole with H/V Correctors
o Robin Wines got her magnetic model of the Sextupole
to work. Interpreting data and optimization, if
necessary, are to follow.
WBS 10 (Wiggler):
Coils for the dispersion section were completed
but snowed-in up in New Hampshire. Coils will be shipped to PECO
the end of this week where the core is waiting. A model for the wiggler
is being developed in Radia to
determine the best solution for the field bias
issue. Design is progressing on the measurement stand. No decision
has yet been made (Karn and Benson) on whether the existing Group-3 Hall
Probes are acceptable or whether a dual axis probe needs to be purchased.
WBS 11 (Optics):
We are finishing review of the check prints for
the deformable mirror assembly, and plan to release the drawing package
next week. The design team continues to work on the upgrade optical
transport system (OTS) and
optical cavity assemblies.
During operations this week, with extended operation
at modest laser power (~ 100 W cw), we found that the O-BPM ADC electronics'
limited dynamic range made their use problematic. We are going to
work with I&C
on this, and in the short term install a larger
range of neutral density filters.
As mentioned in the Jan 8-12 weekly brief, we replaced the black-anodized Al mirror holders on the collimator linear stage with unanodized holders. This was done because it appeared that most of the beam drift we observed came from the collimator, and the black-anodized mirror holders, with their high CTE, were a likely candidate. Our operational experience this week has shown a greatly reduced drift, compared with our run in November. So, this lends credence to our specifications in the upgrade OTS that all mounts be either temperature stabilized or made of low CTE materials.
Operations/Commissioning:
The machine availability this week for the continuation
of the user run was good. See the highlights and Optic sections for
details.