The FEL Fall User run started this month (and continued until Nov. 10). Experiments were carried out on: (1) the production of carbon nanotubes, (2) a test of efficacy of 2.94 micron radiation for corneal ablation; (3) polymer ablation studies; (4) and x-ray production by Thomson scattering.
The ONR/DOE semi-annual project review committee was held on Monday, Oct. 23. According to our ONR contract monitor, John Albertine: “the bottom line--it looks like the project is going well”. Details will follow when the committee report is filed.
Project Cost Performance
The project budget for the period June 1, 2000
to Sept. 30, 2001 is $9,029k. The project through the month of October
has a total of $1,560k of performance scheduled (assuming the project started
at the originally planned start date of April 1, 2000). The work
performed through the end of October was $1,576k, which is 17% complete
vs. 17% scheduled. The actual cost accrued through October totals
$1,463k. This results in a schedule variance of +$16k and a cost
variance of +$113k. The favorable cost and schedule variance continues
because of the large quantity of RF work (WBS 6) that was completed ahead
of schedule and under cost. Work in Beam Transport (WBS 9) and Optics
(WBS 11) will continue to show minor negative schedule variances until
we recover from the late project start and the engineering change request
for the optical cavity design approved at the Oct. 23rd review.
On Oct.12-13, the management of the FEL project
participated in a workshop on "Scientific Applications of Accelerator-driven
Light Sources" in Washington, DC, sponsored by DOE, SURA, BSA, and LBNL.
WBS 3 (Beam Physics)
We came up with a cost-effective modification of the baseline lattice that can accommodate the addition of a chicane for the UV wiggler/optical cavity. This concept was presented at the Oct. 23 project review as a precursursor to an engineering change request to the baseline (Rev. 1.0) lattice. Integration of UV and IR systems involves a UV bypass as a single-dipole parallel translation with dispersion suppression via dispersion modulation. Geometry and electron beam optics based on the Revision 1.0 IR driver design were developed and a layout was sent to engineering.
Data derived from a recent emittance algorithm test was (crudely) reduced and suggests electron beam emittances in the backleg of ~10-12 mm-mrad horizontal and ~3 mm mrad vertical. Planning proceeds to refine the measurement algorithm in support of CSR studies.
Following the Oct. 23 review, activities centered on an examination on performance limits in energy recovering linacs, with particular attention on linac dynamic range in as much as this parameter is 5 times larger in the Upgrade than in the demo (10 MeV:200 MeV vs. 10 MeV:40 MeV). It was determined that a very large injected/final-recovered energy ratio could be supported through the use appropriate external focussing in the linac.
WBS 4 (Injector)
We started preliminary design work on the option
of putting a cathode shield and cesium channels into the ball cathode.
We are running further tests on the N2 implanted electrode with a 6mm gap
at 20MV/m, completing a 7 hour run at 20MV/m on a 6mm gap with an average
current of 90pA. We ran 5.5 hours test at 30 MV/m with a 4mm gap.
The current averaged about 50pA with a small amount of activity
once in a while, which could be conditioned out. This is very encouraging results for use of this treatment for the upgrade gun electrode design. After completion of the above tests we installed the 2nd N2 implanted electrode into the test system and prepared for a second test at 30 MV/m.
WBS 5 (SRF)
We completed the technical discussions with the vendor chosen for the waveguide couplers. The final contract can now be written. We received the proposal from KEK and dispatched a response concerning KEK’s interest in electropolish treatments of the FEL module SRF cavities. KEK has recently obtained gradients exceeding 30MV/m with a 9 cell 1.3GHz cavity. A letter of intent was sent to KEK which indicates Jefferson Lab’s interest in the KEK proposal in exchange for test data on the cryomodule performance in the FEL.
We received weld coupons from PHPK for qualification of helium vessel heads and a sample vessel head. This was followed by a visit to PHPK to inspect the 1st article helium vessel prior to shipment to Jefferson Lab.
WBS 6 (RF)
All 8 klystrons were installed in zone 4 and the filament circuits were tested. Shorts were placed on 4 of the 8 waveguides. The debug and test process was started on zone 4. Installation efforts continued in zone 3.
The vendor for the current FEL gun high voltage power supply, Glassman High Voltage, has agreed to provide us a slave unit to work with one of our existing drive units. We will send them the multiplier and measuring stacks along with the drive so they make any necessary changes. They will integrate and test the system at their plant. We will make any final modifications after it is installed again here.
The RFP was issued to upgrade the HVPS for the
100 kW klystrons.
WBS 8 (I & C)
Cables for the Optical Beam Position Monitors
(OBPM) have been installed. The 32 channel VME board design/layout
is complete and is in production.. The commercial 64 channel A/D
boards arrived, the software is ready to go - there were only minor differences
from what was already in use. The design for the LiTaO3 detector
preamp and board design is complete and was sent out. The "beta"
for the system should work down to 100 microseconds, more effort will make
the optical diagnostics fully operational down to 10 microseconds.
An alternative positioning system has been brought on line - this is based
on the Spiricon Pyrocam. By connecting the output to the MaxVideo
VME video processor
one can track X & Y position..
Other improvements to the user lab include picomotor
controls for 32 additional steering motors, there will be cables and mux'd
outputs for up to 8 motors per lab. The user LAN has been wired for
4 ports per user lab. This will allow remote control of users data acquisition
PCs from the control room or any other
lab and allow web access and email without an IP address.
The components for the vacuum controls and ion pump power supplies have been arriving, these are being stored in the FEL building prior to shipping out to a local fab shop for assembly. The 3" BPM detector documentation is being sent out for bids.
The Request for Proposal (RFP) for the 3" shielded
beam viewers - all 37 pages- is complete and was signed off 10/13/2000.
This was sent out to shops for bid. Procurement packages for the 3” Beam
Position Monitors and the mechanical packages for vacuum control hardware
were worked on. The Laser Safety Systems (LSS) have been gone over
in agonizing detail, there were very minor differences
in some of the local Programmable Logic Controller (PLC) boxes, and hence unique code. The code from lab one was installed in the other "hutchless" labs and the minor changes were done to bring all units in agreement to the drawings. The logic in lab 3 is unique since it has a hutch. All four labs passed all of the required certifications.
WBS 9 (Transport)
Change of Plans for prototyping and drawing packages: Background:
1. The dipoles in the corners of the IR machine
where the beam for the UV beam exits and re-enters have a new requirement
imposed by the UV beam optics. They need to run at half field, making
beam exit and enter at 21 degrees to the return leg. The pole width
needs to get wider at that end of the magnet to
maintain the 1 part per 10,000 field in the region of the angled beam.
2. The magnetic model has given us confidence that we can add shims to the edge of the poles and combined with the recommended pole width, achieve the magnetic tolerance in this "H" style magnet.
3. The optical chicane and Pi Bends are planned to be window frame dipoles where we only achieved our tolerance in the IR Demo by the use of a Purcell Gap and µ metal pole tip. since models of the Purcell gap never were able to benchmark this field uniformity gain. These are the magnets that need prototyping.
We will make all four GX magnets like the two
for the UV beam to save time in contracting, fabrication, inventory and
measurement. We will not prototype these GX magnets. We will
draw up the GW magnet in house for prototyping with various higher field
replacement metals for the µ metal. We will set aside the
now obsolete GX drawing package as a template from which an outside designer could make the GQ and new GX drawing packages. We started generating the GW layout, concentrating on the differences with the GX. Those areas are the saddle coil leads and the field clamps. We generated the initial GW 3D layout making considerable progress in integrating leads, bus, cover, hoses and bolting. We started making the magnetic model of the GX where we will try to modeling two candidate materials for the Purcell gap pole faces to achieve the uniformity in a window frame magnet.
Budgetary Quote: Everson has given us a budgetary
quote on the 3 inch bore quadrupoles that is considerably higher than our
budget, mostly in the core manufacture. This validates our original
intent to machine the core quadrants on our own new computer controlled
milling machine on an off hours basis to
bring machining costs down.
Our radiation expert is calculating the reflected radiation from severely tilted dump faces as a means of spreading the heat load to larger areas so that the technology of our existing 50 kW dump can by used to absorb the Upgrade's 100 kW.
We took a count of the vacuum hardware for the machine so that the bulk purchases could start.
Magnetic Measurement Probe:
Probe material was narrowed down to two choices: Pyrex® glass (as previous probes) or a reinforced plastic compound (Ultem PEI 2300.) We will pursue getting samples of both materials to test machinability and bonding. The JLab Shop offered to help test samples but their workload will not permit fabricating the final probe.
WBS 10 (Wiggler) .
Bids were received and evaluated for the dispersion section and the contract has been awarded to PECO. Delivery is expected before the end of the December. An engineer was assigned to monitor the fabrication of the dispersion section. The steel for the dispersion section was cut by the machine shop and sent to PECO. The decision was made to measure the optical klystron in house using a Hall probe. We now need to decide which Hall probe to use and how to move the probe through the optical klystron.
Assembly: Awaiting modified clamp hardware being fabricated.
Drawings: details of the manifold ends and modifications of the straight parts were signed off.
Manifold brackets and buss bar mounting plates are next.
WBS 11 (Optics)
The optics team has updated the Project Requirements Document for revisions to the optical cavity section which reflect our new data on low loss optics.
The O-BPM's mechanical assemblies were received, and cleaned for vacuum use. One will be installed in the Optics Control Room (OCR) and one assembly in the accelerator enclosure. A contract was awarded to Advanced Energy Systems to complete the deformable mirror design we plan to use for the HR mirror.
The mirror test stand vacuum enclosure prints are done, but we need to confirm several of the internal component placements before sending the package out for bid.
We've learned that the all-reflective condensing telescope in the OCR efficiently transports harmonics to the autocorrelator, and prevented us from obtaining data. Filters will be procured to remedy this. The 50:50 beamsplitter, which worked well at 5 microns, is more like 25:75 at 6 microns. It will be replaced as well.
Michelle Shinn attended the 32nd annual symposium
on optical materials for high power lasers (aka The Boulder Damage Symposium).
This is one of the best forums for learning the latest improvements to
the robustness of laser components to optically-induced damage. Also
visited were two optical vendors we have used in the past; Rocky Mountain
Instruments and Alpine Research Optics in order to acquaint them with our
optics requirements. Both companies are interested in continuing
to work with us.
We initiated the fall user run with hot check-out the week of Oct.2-8, followed by start of operations on Oct. 11. The run was scheduled to end on Nov. 10th (and did.)
We made measurements of the harmonic power produced by the FEL as a function of detuning. In addition to confirming the physics this information is needed for lab safety calculations. We installed an X-ray setup suitable for 15 keV measurements. We also received our new 5% outcoupling mirrors for producing high average power at ~ 1.05 microns.
We provided 3 micron beam to a group from William and Mary, NASA and Penn State to produce a sizeable amount of carbon nanotubes in both cold and hot cell configurations. A group from Duke investigated reduction of collateral damage in corneal ablation tests at 2.94 microns. These were our first tests on biological samples. Both groups had follow-up experiments the following week under 6 micron conditions. Mike Kelley was given time to continue his experiments on polymer ablation.
In a one-day experiment, Thomson scattered x-rays
at 12.7 keV were detected for the first time using 3.1 micron IR FEL radiation.
Our previous FEL generated Thomson x-rays - at 5.12 keV - were produced
using 5.1 micron light. This run clearly demonstrated capability
the Jefferson Lab's FEL to produce Thomson x-rays simultaneously with IR
AND over a broad tuneability range.