IR FEL Monthly Report for March 1997
Navy IR Demo Contract WBS Elements
WBS 1 Project Management
Fred
WBS 5.0 Instrumentation & Controls
The stripline BPM contract is 80% complete, the 25
detectors are at the Electro-Discharge-Machining (EDM) shop now, this step
will be complete by Monday 4/7/97. The remaining steps are
electro-polishing and final welding. The delivery will be on time. In
response to the change in ITS operation schedule the multislit emmitance
monitor was installed in the 500KeV beamline for system tests during the
upcoming run. The hardware and software for making this measurement has
been tested with simulations. The cavities used to determine bunch and
path length are scheduled for delivery in July, the supporting electronics
are complete and being bench tested. Procurements for the odds & ends
continue, all of the CCD cameras and enclosures are on site, there is some
machining yet to be done.
Personnel Safety System: The PSS design review was held on April 1 & 2.
This review was for both the Personnel Safety System and the Laser Safety
System. The report was very favorable with concerns mainly focused on
containment of the FEL output. The PSS box duct is complete downstairs,
wiring will begin in mid-April. Fabrication and procurements are at the
90% level with the documentation essentially 100% complete.
Machine Protection System (MPS): The MPS system design and documentation
is slightly behind schedule, this is partially due to the same people
working on the PSS which is required prior to the MPS system. The
procurements are proceeding from Argonne, the conversion of the Beam Loss
Monitor (BLM) board should be completed in April.
Control System Hardware: Most all of the control racks, other than those
in use in the Injector Test Stand, have been moved to the new building.
The fabrication and labeling continues on these racks. The layout for all
of the control crates and network design continues.
Control System Software: Progress was made on gun high voltage control,
remote drive laser control, and on the software for the machine protection
system is being debugged on borrowed MPS boards from Argonne.
DC Power: The 5 trim rack power supplies (each 32 channel) are complete,
load tested, and moved into the FEL building. The drawings have been
finalized for the trim magnet nomenclature, this database with be turned
over to the software group for programming the database. The
injection/extraction power supply requirements were revisited resulting in
savings of ~$16K.
Vacuum Controls: The vacuum crate design is complete and being reviewed
prior to fabrication. The vacuum database is also being reviewed prior to
submitting it to the software group.
WBS 6 Cryogenic Distribution
1) Welding of linac transfer line modules started. The 2 kelvin circuits of
both the supply and return lines have been leak tested. The Sheild Circuit
inner pipes for both have been welded and are being leak tested.
2) Installation of the sleeve supply and return transfer lines has begun.
They are being "preinstalled" by completing all the long duration welding
and leak testing before the sleeves are installed.
3) Detail design of the feild flex can was completed. All procurments are
awarded and fabrication has started.
4) Installation of gas lines in the tunnel is complete except tie in to the
sleeve gas lines which can not be done till the sleeves are in.
5) Installation of the Gas lines at CHL nearly complete.
6) Total of PR's for March was $45,000. This should be the last
big month.
7) All procurements for instrumentation and control are complete.
Fabrication is 75% complete. The next phase is in the building when it is
available.
8) Mechanical fabrication/installation crew size for March was 11.5 people.
Next month will be the start of the decline.
WBS 7 Beam Transport
G. Biallas
WBS 8 RF Systems
1. The Chopper system was operated in the CW mode at 40 watts
for the bunch length and longitudinal experiments this past month.
2. The software for the Quarter was refined and tested this month.
All of the interlocks are now being displayed on the major RF
screens. The mechanical tuners and heaters are to be tested in
April.
3. The spare 50 KW klystron is still at TJNAF waiting for a return
authorization from the vendor.. It has a vacuum leak and needs
major rework.
4. The trip to Hipotronics produced the desired result of getting
the vendor started on the 225 KW variable DC power supply. The
major components are now on order and the design review is scheduled
for April 17th.
5. A warm window, tested to 25 KW, was installed on the Quarter
and the RF waveguides were connected. The Quarter will be cooled
and SRF commissioning started in early April.
6. A Cathode Power Supply, a High Powered Amplifier, and 2 sets
of Low Level RF racks were moved into the FEL building. All of
this equipment is complete and tested. They will be connected
when the building is more complete.
WBS 9.2 Injector Move
S. Benson
WBS 9.4 Wiggler
S. Benson
WBS 9.6 Optics
M. Shinn
Injector, SRF, Facility, and Other
Activities Outside Navy IR Demo Contract
INJECTOR TEST STAND
Reconfiguration of the photocathode gun with a new high-voltage stack and
field-emission- resistant coated cathode support tube was successfully
accomplished by month's end. As of 31 Mar 97 the gun was under vacuum and
was being readied for high-vacuum bake-out. The experimental beamline had
been stripped of diagnostic hardware in preparation for the bake.
Moreover, a cesium response was obtained on the gallium arsenide disk
(which underwent an atomic-hydrogen cleaning as an alternative for the
previous chemical-cleaning procedure).
Prior to opening the gun, we continued operating it 250 kV, making several
classes of measurements. We did a set of transverse-emittance measurements
to investigate the relationship of the gun solenoid field to beam
emittance, particularly in the region around 20 pC/bunch. The data suggest
a strong sensitivity for emittance to solenoid strength and were passed to
the modeling effort for explanation. We made several measurements of bunch
length versus transverse position at low charge per bunch. These
measurements were in close agreement with the laser autocorrelator signal,
giving an indicated one-sigma bunch length of 23 ps with the laser cavity
optimized. We also did a longitudinal emittance measurement at low charge
per bunch, thereby verifying the software and technique necessary for the
measurement. We calibrated the viewers for the multislit
transverse-emittance diagnostic which will be commissioned with the
upgraded gun. (Assembly and alignment of the multislit
transverse-emittance diagnostic in the gun's experimental beamline was
completed.) In the process, we generated a test set of multislit data
using the existing slit assembly to provide example data for analysis. We
did a continuous-wave run to test photocathode life, and in the process
delivered 10 C to the beam dump. This run was controlled and monitored
from the Machine Control Center (MCC) on the accelerator site. We started
to integrate lessons learned from running the ITS from the MCC in
preparation for routinely running from the MCC in the future with support
from the Operations Department.
We completed software development for remote control of the photocathode
gun's high-voltage power supply, including provisions for status updates
and current-limit and voltage-ramp-up controls. Remote control of the
power supply for the first electro-optical modulator was likewise
completed, as was the rf attenuator for this modulator.
Progress on the photocathode drive laser consisted of enhancements to
existing diagnostics. Upon determining that the second high-voltage-bias
supply for the electro-optic modulators (EOMs) had failed, we returned it
to the vendor for repair and were anticipating imminent receipt of a
new-style EOM. It would account for our finding that the modulator's
thermal blooming problems were related to the indexing fluid used in their
manufacture. In turn, a dry design was being fabricated by the
vendor.
Possibilities for improving the rf-phase-reference system of the
photocathode drive laser were developed. The objective is to reduce the
laser's high root-mean-square phase error. The circuit is observed to
oscillate at around 800 Hz, corresponding to the second pole in the system.
Plans are, by the end of April, to decide on a set of experiments to try
to solve the problem.
We made considerable progress developing and using test stands for warm
windows. By mid- month we thought we had two good warm windows for use in
the cryounit because they passed qualification testing up to 25 kW.
However, one of the two "good" warm windows broke on 16 Mar 97 at 30 kW on
the 50 kW klystron test stand.
In view of the window breakage, we decided to proceed by qualifying fully
the surviving window to nominally 20-25 kW, installing it on the cryounit,
and subsequently doing all the planned experiments per existing schedule
using the one waveguide-window assembly. By month's end, the window was
installed in the cryounit, and cool-down was imminent, scheduled to begin
Monday, 1 April, with cold testing to follow. Meantime, we are vigorously
pursuing warm windows to 50 kW by, for example, getting consistent ceramics
from vendors, further klystron testing, etc. It is not a problem to have
warm windows to support first light; 20 kW windows will be OK
for 1.1 mA beam.
WBS 3 Cryomodule
Joe Preble
WBS 2 Beam Physics
Beam physics activities for the month fell into four general categories:
continuing development of CSR theory, extensive documentation of the
lattice design, cursory looks at machine upgrades for high-power operation,
and further simulations of the IRFEL beam from gun to wiggler.
CSR theory is being generalized with the goal of developing a computational
many-body simulation tool. This is a very challenging task! Important
CSR-interaction physics exists both at the local scale and at the global
scale, and this means there is a need for judicious use of embedded
configuration-space meshes. The current focus is developing an algorithm
and testing it against special-case analytic solutions that we've
discovered over the past few months.
By month's end, documentation of the lattice design was nearly complete,
with plans for posting in on the www FEL Page early April.
Thinking continued concerning pathways for machine upgrades to higher
powers, and this thinking has been closely coordinated with
Northrop-Grumman as part of developing an overall Navy FEL Program Plan.
Notional lattice designs have been proposed, as well as notional
injector-development plans. All of these ideas will eventually need to be
hardened were the Navy Program Plan to be adopted and implemented as it
exists now.
Further, and continuing, modeling of the IRFEL is underway. To date we
have found a number of solutions, i.e., sets of machine settings, that are
compatible for first light and support the commissioning plans for first
light. We have now begun to consider full-power operation in depth. By
month's end, some initial trial runs had been made and were being analyzed.
This effort will continue as a natural part of planning for commissioning
and operation.
WBS 4 Commissioning/Operations
We began to organize the experimental plan for the ITS during May. The
"MUST" for this run is to measure transverse and longitudinal emittances,
as well as bunch length, at bunch charges of 1 pC, 60 pC (corresponding to
first light), and 135 pC (corresponding to full power). In addition, a
series of photocathode-lifetime tests are planned, as well as possible
experiments at gun voltages exceeding 350 kV. Dates have been set for 24
hour operation in the ITS.
A procedure for setting up the electron beam prior to wiggler installation
was drafted. Part of the consideration is doing early experiments
concerning the effects of coherent synchrotron radiation on the electron
beam. The quad-viewer method for making transverse-emittance measurements
in the back leg of the recirculation arc was detailed, and correspondingly
the precise locations of the optical-transition-radiation viewers were
pinpointed. Generally speaking, we have now frozen the precise locations
of all of the elements of the beam-transport system, which needed to be
done as part of implementing the installation plans.
We began detailing plans for implementing the machine protection system.
The hardware approach has been chosen and is based on a combination of
CEBAF detectors and existing Argonne National Laboratory VME-based detector
boards. In addition, we detailed the hardware requirements, plans, and
procedures for the Personnel Safety System (PSS) and Laser Safety System
(LSS) for the IRFEL in preparation for the PSS/LSS Review scheduled for 1-2
Apr 97.
Considerable progress was made in planning the Accelerator Readiness Review
(ARR) process, especially as regards its purpose and sequence. Operation
of the accelerator is envisioned not to be contingent on completing the ARR
process. Rather, the ARR process is intended to allow routine and
productive operation of the entire system, which means we can commission
without going through the entire ARR. A www-based system is envisioned to
be the vehicle for implementing and monitoring the ARR process.
Facility
G. Neil
Upcoming Meetings and Reviews
Navy Laser Safety Meeting, Jefferson Lab, April 15-17, 1997
Navy High Energy Laser Office Project Review, Jefferson Lab, April 15, 1997
SURA Board of Trustees Meeting, Washington, April 16-17, 1997
SURA Maritime Technical Advisory Committee, June 10-11, 1997
SURA Science and Technology Review, July 15-17, 1997