IR FEL Monthly Report for February 1997

Navy IR Demo Contract WBS Elements

WBS 1 Project Management

February 1997 was the eighth full month for the IR Demo project funded by the Navy.

The IR FEL Demo project through the month of February 1997 has a total of $4,209k (less SRF and building) of cost performance scheduled. The work performed through the current period is $3,524k or 44% complete of 52% scheduled. The actual cost accrued through the current period is $3,649k. This results in a schedule variance of -$685k (an increase of $71k) and a negative cost variance of $126k. The net change in the cost variance is -$298k, going from a positive $172k to a negative $126k.

The building construction schedule in the performance reporting schedule is less aggressive than the actual contract schedule. In the performance schedule the contractor remains essentially on schedule. However, we expect BOD #2, occupancy of the second floor, will be 2-3 weeks behind schedule. The building is being reported as $23k behind schedule and $48k undercost.

The performance measurement reporting system for the project was reviewed in preparation for the January monthly report. Using the secondary peg points with dollar values below the previously reported primary peg points ($100 K or more in value) significantly improved the cost performance data for the project. A previously reported negative cost variance was an artifact of taking credit for only primary peg points. The January monthly report was completed and distributed on Feb. 28th

The DOE Basic Energy Sciences Program Office held a review of the IR Demo project and the Jefferson Lab FEL program on Feb. 23-25. The review was co-chaired by the Navy (John Albertine) and included six external reviewers. The review team gave the project excellent marks for the execution of the Demo project to date. A draft report is expected from the Team early in March. Dylla and Helms have been invited to DOE-BES headquarters on March 6th to discuss continued interactions with BES.

A draft Field Work Proposal for FY98-99 support of the IR Demo User Facility was forwarded to the DOE-BES Program Office for comments.

A draft report from the meeting of MTAC on December 18 was received from SURA. Comments were returned to SURA and the Navy HEL Office. The committee urged the Jefferson Lab team and our industry collaborators to work with the Navy Program Office to strengthen the long-range plan for further discussions with Navy officials and congressional staff.

It was decided to defer all 10 MeV injector operations with electron beam to the FEL Facility, and to concentrate activities in the Injector Test Stand (ITS) toward maturing the technology for the photocathode gun and establishing reliable operations of the gun. Complete testing of the cryounit without electron beam will also take place in the ITS as originally envisioned. Plans are to move all gun and injector hardware to the FEL Facility starting 1 June. These injector activities preserve the milestone of installing all hardware in the Facility by 30 Sept. 97.

At the SPIE Conference on High Power Lasers held in San Jose on Feb. 11-15, G. Neil presented a talk on modeling of the optics for the IR Demo. M. Shinn gave a status paper on the IR Demo Project. Related papers were given by J. Albertine, J. Cook, A. Todd, and M. Kelley.

On Friday, 7 Feb., C. Bohn presented a colloquium at the Naval Postgraduate School entitled "Collective Effects in Electron Beams for High-Power Free-Electron Lasers" and participated in discussions of a tutorial nature on coherent synchrotron radiation (CSR). The following Monday, 10 Feb., Bohn attended a meeting at SLAC concerning research and development for the Linac Coherent Light Source (LCLS), where he presented a talk entitled "Survey of Jefferson Lab's IRFEL and Coherent-Synchrotron-Radiation Studies". CSR experiments planned for the IRFEL are also of high interest to the LCLS, as was highlighted in discussions at the meeting.

WBS 5.0 Instrumentation & Controls

Beam Instrumentation: The beam position monitor mechanical contract was awarded to Breezes Precision Boring. The terms call for 60 day delivery, a visit was made 2/28/97 to discuss the details for the assembly. The vendor will have all of the required materials in house by March 3, there has been ample work completed to assure the delivery on April 18. There are three tasks sub-contracted out: the stress relieving, EDM cutting of the stripline slots, and the electropolishing of the subassembly. These will be tracked to assure timely completion.

The beam viewer assemblies were received Feb. 27. A sample will be leak checked and connected to an RGA (residual gas analyzer) to assure proper procedures were used during the cleaning and assembly. These 13 devices have been delivered complete to minimize the draw on internal manpower.

The M56/M55 system is progressing well, the modulator chassis is complete, receiver chassis is being debugged and the firmware is being developed. The two cavities required should be complete in late April or early May.

The multislit emmitance monitor parts are now complete, the 52 slits (two devices; 13 each horizontal and vertical arrays) were successfully machined to +/- 2 microns. These devices will now proceed to assembly. The software has been tested by using PARMELA output as a signal and viewing with the CCD camera that will be used in the accelerator. Due to the deferred 10 MeV testing this device may be tested as a part of the expanded 350 KeV+ test plan. It is desirable to complete as much system checkout as possible.

Personnel Safety System: A review date of April 1 has been set for the Personnel Safety System Review. This review will also cover the Laser Safety System (LSS) used to interlock each of the optical labs. The PSS racks have been relocated to Zone 15. This will make the connection to the Main Control Center (MCC) much easier.

Machine Protection System: The procurement for the Argonne system is proceeding, we have single pieces of this hardware in house to facilitate the software efforts. Discussions are ongoing to define the different states of machine operation and how this interfaces to the drive laser controls.

Controls Hardware: The computer procurement award was delayed due to discount confusion between Jefferson Lab and Hewlett Packard. This has been resolved with delivery scheduled for April 21. The detailed VME & CAMAC crate assignments are being finalized as well as the cable database for installation.

Software: Excellent progress is being made on all of the systems. By deferring the 10 MeV beam tests the software resources will not need to be diverted to the injector test stand, this will further enhance the timely completion of the systems needed for commissioning.

DC Power: The order was placed for the remaining two 100 Amp chicane power supplies. The delivery is expected to be six months (this will be tracked closely). The trim racks are nearing completion, cable assemblies will be fabricated in the service building to connect the 32 channels per rack to the termination blocks located in the tunnel. This will reduce the time required to install the system once the FEL building is available.

Vacuum System: The cable database is nearly complete, the rack layouts are finished and the detailed crate design is proceeding. The 50 beam line ion pump controller (BLIPC) printed circuit boards are complete and being tested. This board was re-laid-out from the old artwork and assembled off site. The next boards due are the gate valve controller cards.

WBS 6 Cryogenic Distribution

Quad transfer line installation is complete. All linac transfer line modules are fabricated and have all been placed in the linac. Welding will start after confirmation from survey and alignment that the positions marked for the location of the transfer lines are correct. Fabrication of the sleeve supply and return transfer lines are nearly complete; just the final leak tests remain. Detail design of the field flex can should be complete by 3/10; most of the required parts have been procured. We have started installation of the gas lines at the CHL. All procurements for instrumentation and control are complete. Fabrication of the cryogenic distribution system is 65% complete.

WBS 7 Beam Transport

The electron beam optics of the machine in the optical chicane region were changed slightly to allow the space for the shielding in front of the optical collimator. The shift does not affect clearance to other features of the optical cavity or the design of the dipoles.

For dipoles, the bidders received solicitations for the optical chicane dipoles as design work continued on the remaining reverse bend, 180 degree and injection/extraction dipoles

At the Magnet Test Stand, 304 stainless steel qualified as the vacuum chamber material of choice after tests in the prototype dipole. The prototype trim quad underwent detailed magnetic measurements which require extensive analysis over the next weeks. The prototype sextupole went through preliminary magnetic characterization with the conclusion that we will need field clamps, but the basic design is sound. In the opinion of L. Harwood, exact pole tip shape will need further work, but fabrication and installation can proceed.

The first article of the main quads arrived from the vendor. It passed magnetic tests.

A kick-off meeting was very productive for design of the stands for magnetic elements downstream of the cryomodule.

For the vacuum system, the differential pump station was signed off and design of the vacuum chambers in the remaining first light regions started. Substantial portions of the vacuum hardware have been ordered.

The review of the dumps was held on the on February 5. Several issues involving protection of dumps or the collimator that are not designed to withstand the full beam intensity or an odd beam distribution were identified and require further study.

WBS 8 RF Systems

The chopper system was operated with its new software in both the CW and pulsed modes. In the CW mode, the cavity can only take 100 watts before the pressure becomes excessive. The stainless steel outer conductor of the drive probe is the suspected problem even with cooling fins. In the pulsed mode, the cavity has received 380 watts without a vacuum problem.

New software for the quarter cryounit was successfully tested this month. The tests for the mechanical tuners will be tested after the quarter cryounit is cold.

The spare 50 kW klystron did not pass its acceptance tests. It appears to have developed a vacuum leak and will have to be returned for rework.

Hipotronics still expects to deliver the first unit of the 225 kW variable DC power supply in May 1997, but there has been little evidence of progress. A trip to the vendor is in order. The design review is tentatively scheduled for the latter part of March.

The installation schedule for the FEL building is approximately 50% in place and starting to be helpful.

WBS 9.2 Injector Move

The purchase order for the high voltage tank fabrication was awarded. Delivery is scheduled to be in mid-May.

The purchase order for the laser clean room fabrication was awarded to Clean Air Technology. It is scheduled to be complete by June 1.

Work continued on injector layout design. About 50% of the design work is complete.

WBS 9.4 Wiggler

Sent out requests for quotation on the wiggler vacuum chamber tubing. The vacuum chamber support design is 60% complete.

STI Optronics has completed all the mechanical components for the wiggler. Some parts still have to be anodized. Assembly has begun on the supports. STI Optronics has received and measured most of the magnets from Shin-Etsu. The uniformity of the magnets is excellent. The final set of magnets is due around March 10. Final magnet measurements are now scheduled for early April.

WBS 9.6 Optics

During February, activities concentrated on completing the designs for the optical transport and diagnostics. The turning mirrors ("mirror cans") and diagnostic pickoff drawings were signed and are in Procurement. The redesigned collimator did not pass our initial internal review, and is being redesigned. We completed the drawings for installation of the optical transport pipe; with installation occurring sometime in March. Procured parts continued to come in, major acquisitions were the ion pumps, the linear stage, and the monochromator/spectrograph. Software development for the optical cavity controls continues. With much of the optical cavity fabrication complete, we are beginning to assemble the parts to check for fit. The Mach-Zehnder interferometer is being reassembled on a small (19" x 23") optical breadboard for testing with an 8 m separation between the folding mirrors and the beamsplitters.

ITS

The photocathode drive laser was operated in support of transverse emittance measurements. The IR and SHG powers were quite stable. The divide-by-two electro-optic modulator, with it's new lithium niobate crystals was installed and found to steer the beam to an unacceptable degree. It was returned to the manufacturer, repaired, and when installed, found to handle the nominal 20 W of IR without problems. We are having problems matching sufficient rf into the modulator to get good modulation, and are working this issue. We could not duplicate last Summer's locking of the laser's phase to the master oscillator, although performance was acceptable for the initial longitudinal measurements. The rf group is looking into the problem.

Injector, SRF, Facility, and Other Activities Outside Navy IR Demo Contract

Injector Test Stand (ITS)

The month's activities were focused on three areas: reconfiguring the experimental beamline of the gun to permit both transverse and longitudinal phase-space measurements, acquiring the components necessary for upgrading the gun to operate at photocathode stand-off voltages of at least 350 kV, and developing warm ceramic windows for use at 50 kW on the injector cryounit. In addition, we received the spare 50 kW klystron and began running it through a series of acceptance tests. Also, the software and screens for the cryounit were successfully tested, and the software for the mechanical tuners was installed.

We succeeded in reconfiguring the experimental beamline of the gun and readying the gun for renewed operation at 250-300 kV stand-off voltage. The existing ceramic stack was processed to 320 kV, and all of the components and software for the beamline were checked out. We turned on the gun, producing low power electron beam at 250 keV, and began commissioning the new experimental beamline. We checked out the magnets, the drive laser and its upgrades, the diagnostics and rf systems, and we also completed hardware checkout of the new diagnostics, light-box harp, and aperture. Good extinction ratios were also achieved of unwanted ghost pulses from the drive laser.

We then started 24-hour operation of the photocathode gun at 250 keV, running three full days during the last week of February. In conjunction with gun operations, we aligned the drive laser to the photocathode, hard aperture, and camera in the test cell to permit laser-beam analysis. In general, the drive laser was brought back to a fully operational state. We also recesiated the cathode and brought it back up to several percent quantum efficiency. Subsequently, we made about 20 measurements of transverse emittance to verify the performance of the new hardware in the beamline and the reproducibility of measurements taken last November, and to quantify the effect of the rf kicker cavity on the beam. No effects were observed which are directly attributable to the kicker cavity. The kicker cavity itself was commissioned to perform as required for longitudinal measurements.

We also vigorously pursued the acquisition of a cathode support tube with field-emission-resistant coating, and new high-voltage ceramics coated for uniform resistivities in the range 5-100x10^9 ohms. These are components that will be used to upgrade the gun to operate at higher stand-off voltages. We received the coated cathode support tube from FM Technologies. By month's end, Lawrence Berkeley Laboratory had successfully produced two coated ceramic cylinders using ion implantation, and they were in process of shipping the ceramics to Jefferson Laboratory.

Development of warm ceramic windows for use in high-rf-power operation of the cryounit proceeded slowly due to technical difficulties with the ring-resonator test stand used to certify these windows. Thus, not only did we upgrade the test stand, but also we developed a new window-test resource based on using one of the 50 kW klystrons to supply rf power to the window test fixture. It allows parallel testing of warm windows in both the resonant ring and ITS cave. By month's end, the resonant-ring test stand had been run with a single warm window and with no vacuum in the system. The window was exposed to rf power up to 50 kW with no breakage. A second window was in testing. Qualification of the 50 kW rf system for window testing was imminent.

WBS 3 Cryomodule

There was, and continues to be, considerable activity toward qualifying warm windows for the injector cryounit. The resonant ring test facility was reconfigured to replicate more closely the vacuum conditions at the window that would prevail during cryounit operation. It was run with a single warm window and with no vacuum in the system. The window was exposed to rf power up to 50 kW with no breakage. This result supports our hypothesis that artificially high vacuum conditions during testing was the cause of limited window performance. At month's end, a second window was in testing. Testing with vacuum awaited further rework of the vacuum test fixture, with first experiments anticipated for early March. In addition, the 50 kW rf system was also configured with a waveguide for window testing in parallel with the resonant ring tests. First experiments with the 50 kW system were also anticipated for early March.

A final internal review of the cryomodule design and existing test results from the injector cryounit was held on 19 Feb 97. No show-stopping issues were identified.

Cryomodule production proceeded generally on schedule. The first cryomodule cavity pair was assembled, and it finished testing during the last week of February in the Vertical Test Assembly. Preliminary analysis of the data was favorable. Gradients were 10 MV/m or higher with little or no field emission evident. The second cryomodule cavity pair is scheduled for assembly during the first week of March.

WBS 2 Beam Physics

Plans were documented for experiments to measure transverse-emittance growth from coherent synchrotron radiation (CSR) in the bunch decompressor following the wiggler location, and in the first recirculation arc. As currently envisioned, the emittance measurements will involve quadrupole magnets and viewers at the wiggler location (with the wiggler removed), downstream of the bunch decompressor, and in the back leg (which has a multiplicity of measurement systems). Parametric investigations of the influence of bunch charge, bunch length, bunch momentum spread, transverse bunch size, and transverse emittance at entry to the bending systems are all envisioned. We anticipate being able to start taking CSR-related data around the turn of the calendar year. In addition, theoretical work continued toward the goal of developing a good algorithm for doing numerical many-particle simulations that include CSR.

As required, simulations were done to finalize specifications for beam-transport components. For example, detailed tracking studies were completed that resulted in a decision to retain the beam scraper and the establishment of its specifications. A second example is a series of simulations of the FEL injector to explore the sensitivity of its performance to the fields of the injection/extraction dipole magnets. This study generated guidelines for the resolution of magnet measurements that will be done as part of the acceptance tests for these magnets once they are received.

WBS 4 Commissioning/Operations

In light of the schedule for producing a new ceramic stack for the gun, we renewed consideration of a deferral of all 10 MeV experiments to the FEL Facility, and ultimately decided to do so. This permits us to do gun development through 1 Jun. 97, as well as thoroughly test the injector's cryounit without beam, and then commission the full injector with beam starting in Sept. 97. It preserves the milestone of installing all hardware in the FEL Facility by 30 Sept. 97, and also relieves some stress on the Laboratory's labor resources in achieving this milestone. Moreover it enables us to improve greatly our confidence in the photocathode gun. The principal disadvantages of the deferral are delays in commissioning and debugging some components of the injector hardware with beam, but these are offset by the advantage of allotting time to work on the gun, the highest-risk subsystem of the FEL.

A new procedure was developed for setting the momentum in the arcs using the air-core corrector magnets that are already part of the baseline design of the arcs. The procedure was posted on www as part of the "arc 1 setup procedure".

Plans were documented for experiments to measure transverse-emittance growth from coherent synchrotron radiation (CSR) in the bunch decompressor following the wiggler location, and in the first recirculation arc. As currently envisioned, the emittance measurements will involve quadrupole magnets and viewers at the wiggler location (with the wiggler removed), downstream of the bunch decompressor, and in the back leg (which has a multiplicity of measurement systems). Parametric investigations of the influence of bunch charge, bunch length, bunch momentum spread, transverse bunch size, and transverse emittance at entry to the bending systems are all envisioned. We anticipate being able to start taking CSR-related data around the turn of the calendar year, an activity that will likely occur in the course of commissioning the accelerator and recirculation loop.

We considered whether to retain the electron-beam scraper in the first recirculation arc and decided to do so. It will localize the potential loss of particles with large energy offsets, as might be produced as a result of the lasing process in the wiggler. Likewise, it provides a nice diagnostic of the wings of the longitudinal phase space emanating from the wiggler, making it a valuable tool for FEL experiments. Specifications were established that permit the scraper to serve as an excellent energy-distribution and halo diagnostic, as well as in its nominal machine-protection role.

A series of sensitivity studies was done by way of numerical simulations as part of developing detailed specifications for the magnet measurements envisioned for the injection-line dipole magnets. The basic plan is to procure these magnets, measure them to now-specified accuracies, and then do follow-on computer modelling that incorporates measurement results to optimize the resultant electron-beam dynamics. There are no significant difficulties anticipated with this approach.

Facility

The month's effort in the facility was focused on getting the steel frame for the upper level completed. Work started in the beginning of the month in the lobby area but by month's end the frame was covering the entire upper level. This sets the stage for the addition of the wall panels to enclose the structure and adding the roof deck. Roof decking and second floor decking in the lobby area was completed. The HVAC compressors were set on their pads and electrical hookup of the main switchgear initiated. The set of completed cryogenic transport lines were transferred to the Facility in preparation for the lengthy installation process. Jefferson Lab personnel initiated the LCW piping installation effort. Schedules were reviewed in a monthly meeting with the contractor. The contractor was sent a get-well letter reminding them that there is a $1500/day penalty on not achieving beneficial occupancy of the second level by Mar 15, 97. The contractor admits to a 3-week schedule slip against the March 15 contractual BOD 2 (upper level). This was primarily caused by problems with one of their subcontractor's miscalculations on the framing. It now appears the upper level will not be fully dried in until the third week of April. The delays in BOD will affect the equipment installation schedule upstairs, cause more work to occur in the summer, and press the availability of installation personnel to keep the schedule on track.

Upcoming Meetings and Reviews

AVS Workshop: Contamination Measurement and Control, Jefferson Lab March 26-27, 1997

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