IR FEL Monthly Report for July 1996

IR FEL Monthly Report for November 1996

Navy IR Demo Contract WBS Elements

WBS 1 Project Management

November 1996 was the fifth full month of activities for the IR Demo project funded by the Navy. A total of $2,497k of costs have been obligated. With respect to the planned accrual of project cost by November ($2558k), $1627k of work was accrued which accounts for 20% of the project completed. The actual costs accrued through November totals $1844k. This results in a negative schedule variance of $932k (an increase over October of $325k) and a negative cost variance of $217k (an increase of $120k). The largest portion of the schedule variance ($568k) is in the Optics System. As explained in last month's report, we expect this schedule variance to be recovered by April '97 without effect on the total project schedule. The remaining schedule variance is accounted for in the variances in Beam Instrumentation ($216k) and Beam Transport ($163k). Additional labor is being applied to both systems to recover schedule. All other IR FEL systems have either a positive or small negative schedule variances. Additional design labor costs which have been applied to the Beam Transport and Beam Instrumentation systems account for the majority of the negative cost variance.

The $3.5M FEL Facility is still running ahead of the established performance schedule: $1,718k of actual costs have been accrued and the Facility is 54% complete.

Several project scheduling activities were quite active this month: (1) a first cut schedule was drafted for all activities that are proposed for the December shut-down of the ITS. (2) a detailed task list for mechanical installation tasks in the IR FEL accelerator enclosure has been completed. This will be followed by a similar list of electrical tasks and a similar effort for the 2nd floor of the FEL Building.

The agenda for the SURA Maritime Technical Advisory Committee was approved for the Dec. 17-18th meeting at Jefferson Lab. A meeting was held with DOE (Dean Helms, R. Marianelli, D. Lehman, and J. Kearns) on Nov. 14 to discuss the planning of the February 1997 DOE Review of the FEL project. The review will focus on building DOE mission support of the project through an emphasis on planning for the commissioning phase and first operational period.

Discussions were held this month with groups from the Vanderbilt IR FEL facility, the Oak Ridge National Laboratory Solid State Division, Argonne National Laboratory Old Dominion University, the Army Research Office and the NASA Langley Research Center about possible collaborations on FEL applications.

WBS 5.0 Instrumentation & Controls

Beam Instrumentation: The complete diagnostics suite has been frozen, we have implemented a change control procedure for any future changes. The BPM review will be held on Dec. 4. This should clear the way for production of both the stripline and button detectors. The mystery on the 1455 Mhz resonance is not yet solved, but needs expeditious resolution so production can begin. The BPM electronics are on track, more Switched Electrode Electronics (SEE) will be ordered. The shielded beam viewer contract is on track for delivery in mid December. The control chassis that interfaces these units to the EPICS control system are proceeding. The bunch length monitor from Uwe Happek (University of Georgia) using a Michaelson interferometer is proceeding well. He will build two units, one will be evaluated in the Injector Test Stand (ITS). The stepper motor controller printed circuit boards (PCB's) are complete, chassis construction is progressing. Huppek will provide man-power to write the required software to enable the measurement to be a single step operation.

Personnel Safety System: Procurements are proceeding, 80% of the hardware has been delivered. The four racks are about 50% complete. These are being built in the end of the north linac.

Machine Protection System (MPS): The hazard analysis continues. Argonne (APS) has agreed to build and test Fast Shut Down (FSD) PCB's and bare Machine Protection System (MPS) PCB's. These will come with operational software drivers (minor changes to configuration and nomenclature). The programmable high voltage power supply was ordered to control the Beam Loss Monitors (BLM). The conversion of this board to VME has begun.

Control System Hardware: A review was held for the computer server & network configuration. The plan was accepted with little changes. We will run redundant servers with mirrored disks to prevent loss of data from a disk crash. Additionally the redundant server configuration will allow for load sharing under normal situations and for either of the servers to take over in the event of a failure. The total cost matches the budgeted amount. These components will be purchased in December. A decision was also made to run the cryogenics IOC network and power directly from the Central Helium Liquifier (CHL). All of the racks for the new building have been delivered. These are being assembled in the north linac.

Control System Software: Progress continues to be made, the software group is working on the priorities for both FEL and work scheduled for the CEBAF machine.

DC Power: The trim rack fabrication is 60% complete. All of the required trim cards will be made available from CEBAF. The BiRa scanners are being ordered. There are no significant changes in software (other the names in the database). We are investigating another option for the 50 Amp power supplies, the manufacturer of our larger power supplies has a 50 Amp version which is software compatible, and nearly 'off the shelf'. This would significantly reduce the burden on the limited resources that are available.

Vacuum Controls: The ion pump power supplies are 50% complete. The fabrication of the vacuum PCB's are proceeding. The crate design will begin in December.

WBS 6 Cryogenic Distribution

Pre-installation tasks for the quad transfer line were completed. All four sections of the tunnel supply TL are complete. We now have 490ft of completed transfer line. Detail design of all return transfer line modules for the FEL building are complete and have been released for fabrication. All materials are here or on order for all returned transfer line modules. Remaining procurements will not impede the fabrication progress. Detail design of transfer lines which go from the field flex can through the sleeves is 85% complete. The first sections of these lines have vacuum breaks. All the material for the vacuum breaks is in. The CHL header extensions were leak tested and are now complete. U-tubes at CHL are 70% fabricated. Detail design of the warm gas lines is 95% and procurements ongoing.

WBS 7 Beam Transport

Dipoles: Work concentrated on establishing the final design of the three styles of Recirculation Dipoles, highlighted by a first pass at a magnet review at mid month. After assessment of the results of magnet measurements, the K value was fixed at 0.27 for recalculation of the final lattice. Measurements of the prototype also revealed that length vs excitation and field flatness were beyond the optics specifications. At month's end, a thicker field clamp is being assessed. It will probably bring the length vs. excitation within specification by eliminating saturation effects. Trials of the prototype with mu metal and a Percel gap at the pole surfaces and of (alternate technology) slots in the poles were being prepared in order to solve the field flatness problem. At the same time, the Northrop Grumman designer is nearing completion of the drawing package for the saddle coil/field clamp style Optical Chicane Dipoles, running about two weeks behind schedule. Any of the above "fixes" can be incorporated in the package with no difficulty. A second review is planned for early December to resolve the issues from the first review. The designs of the injection and extraction dipoles were firmed up. All the measurements on the prototype dipole are now directly applicable to this other class of dipole. Quadrupoles & Sextupoles: The prototype weak quadrupole is finished and awaiting measurement. The prototype sextupole is in manufacture, headed towards an on-time measurement in mid-December. Vacuum: Significant progress was made in designing the Injection Line X Chamber. This is the first of the many rectangular chambers we need. The problems solved and simplifications used on it will serve as a template for the remaining chambers. (However, design on stands and girders for first light lagged while the X Chamber was drawn.) Work continued on interfacing the baked system to the non-baked system in the injector region. Emphasis was placed on determining final quantities of commercial parts so that orders could be placed. As of the end of the month, the requisitions are still being prepared. Installation: Layout of the system with respect to the building utilities ran coincident with the determination of the cable tray locations. The exercise resulted in the shifting many light fixture locations to miss installed apparatus. General: The pace of the system, while up from previous months, is still lagging behind schedule with the outstanding peg points not taken. (Design of quadrupoles and dipoles) Two experienced part time designers were hired to become available December 4, a second is being obtained from Northrop Grumman and a third is freeing up from other work. The design pace should increase. Technical proposals for the weak quadrupoles, which arrived on the 21st, remained unevaluated, preventing placing the order. Reducing the cost from increases in scope still remains an issue.

WBS 8 RF Systems

The Buncher High Power Amplifier (HPA) was successfully tested in both local and remote control modes of operation. A short punch list remains to be completed. The Buncher water skid and controller were tested. They are being modified to improve reliability and performance. The Buncher HPA will be used to drive up to 450 watts to the Chopper cavity. An iris was inserted in the waveguide to attenuate and limit the power to the cavity. This configuration was tested into a load. The Quarter Cryounit HPA was tested in both local and remote control modes of operation. A short punch list and additional software needs to be completed. The IR FEL cryomodule control racks were tested with the 8 kW klystron HPA. A short punch list remains to be completed. Due to an error in the bidding process, the 225 KW variable DC power supply was re-bid this month. The new bids are expected early in December. The final version of the RF software was defined. It is to be tested in December. The procurement for the waveguide flex couplings was placed. We expect delivery to be complete in 8 to 10 weeks.

WBS 9.2 Injector Move

Bids were received for the high voltage power supply pressure chamber that were within budget. The final bids may be slightly higher due to the need for a few more flanges and feedthroughs. The final drawings are being revised with the new flanges and feedthroughs and will be sent out for final bid in early December. We sent out preliminary bid packages for budgetary quotes on a new clean room. The budgetary quote should be here in early December and the purchase requisition can be submitted at that time. Work continued on injector area layout in regards to cable trays, lighting, and optical transport. Suggest changes in the light positions were submitted to the building contractor.

WBS 9.4 Wiggler

The mechanical support design is at the 85% level. The optical bench is being purchased.

A contract is being negotiated with Northrop/Grumman to do the detailed design work for the vacuum chamber and chamber supports. The vacuum pumping requirements for the chamber were derived.

All the detailed drawings for the wiggler have been received and checked. Parts are being machined at STI Optronics. The magnet blocks for the wiggler have been delayed until January but this is not foreseen to delay the final delivery date.

WBS 9.6 -- Optics

This month's activities were devoted to ordering most of the hardware for the optical cavity and for optical diagnostics. Major procurements include; a spectrograph/monochromator, sapphire mirrors for operation at 3 microns, and a pumping system that will be used for the accelerator as well as for evacuating the region near a cavity mirror after it has been changed. Most of the catalog vacuum hardware needed for the optical cavity has been received. The drawings for the optical cavity were revised to incorporate LVDTs (to readback the mirror positions) and ion pumps. They have been approved for construction, and procurement will begin in December. We have begun procurements for optical transport system components. We ordered the tubing and the gate valves, and are soliciting more budgetary estimates on catalog optics, the translation stages in the mirror cassettes, and the beam dumps. A meeting was held to discuss changes in the optical transport collimator, so we can better adjust for differences in the thermal distortion from different output couplers. We inspected the ground floor HVAC penetration, and determined it will necessitate a change in our optical transport layout. We are considering two different schemes and should be ready to incorporate them in December, when we will have designer support.

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

Injector Test Stand (ITS)

During November, the gun was commissioned and operated at 250 keV. In general, difficulties surfaced where they were least expected -- in the drive laser. In an effort to stabilize operation of the drive laser and suppress ghost pulses in the electron beam, we upgraded a number of components, including electro-optic modulators, mirror mounts, and lamps. We then ran the gun routinely, going to two-shift operations. After ascertaining that a top-hat-like transverse profile proved optimal for reproducibility, we extracted a full set of publishable data in support of a doctoral candidate's dissertation. This data is tailored to validate the computer code used to simulate the electron-beam dynamics in the gun. By the end of the month, plans were to attempt operation of the gun at higher voltage, up to 300 keV, prior to shut-down for installation activities and replacement of the high-voltage stack, and to do further upgrades to the drive laser during the shut-down period.

Progress continued toward fabrication of a replacement high-voltage stack that would allow routine, long-term operation at 350 keV. We decided to focus on producing two new ceramics of well-matched, higher electrical conductivities, in anticipation that the higher conductivities would raise the threshold for arcing caused by electrons embedded in the ceramics after field emission from metallic components. By the end of the month, the production of these ceramics was about three weeks behind schedule, due principally to uncertainties in the measurements of the conductivities. At this writing (3 Dec. 96), the stack is projected to be ready on 23 Dec. 96. We are partially compensating this delay by shuffling the installation schedule in the Injector Test Stand to move installation of the stack from the first activity (as initially planned) to the last activity. Other installation activities include putting the cryounit in the test cave for off-line high-power rf tests, placing stands and girders in the cave for the 10 MeV beam line, and installing the beamline for the 350 keV experiments.

Other ITS progress included successfully completing the fabrication and acceptance tests of the cryounit, the buncher cavity, and components for the 350 keV experiments. Comprehensive plans for the 350 keV experiments were also compiled and posted on WWW. Details are discussed in the weekly reports. Much of the activity involving beam physics was focused on refining the design of the transport lattice in conjunction with measurements of magnetic field profiles in the prototype dipole magnet, and the design of the vacuum chamber to allow for installation of the array of electron-beam diagnostics in keeping with the impedance budget. By month's end, sufficient information was available to work toward freezing the top-level design drawing and the lattice. Plans are to include a design of the second recirculation arc that will facilitate a future upgrade to a 75 MeV machine to generate 1 micron light, as well as to add of order 1 m extra length after the cryomodule to enable multipass monitoring that will facilitate machine operations. We anticipate freezing the design by mid-December, at which time we will institute a formal change-order process for proposed revisions. Such a process is already in effect for the diagnostic suite, and it is working smoothly.

A concerted effort was launched to study, by way of computer simulations, the bunch dynamics from the photocathode through the optical chicane, for all operational modes of interest, i.e., both for first light and for full-current operation. The accelerator layout used in the code was updated to reflect the latest configuration since there have been numerous changes in detail over the past few months. Simulations performed by month's end indicate favorable bunch profiles for all peak currents of interest. Computational results concerning the degree of bunching in the optical chicane are in general agreement with analytic predictions based on the longitudinal envelope equation.

Work on the influence of coherent synchrotron radiation (CSR) on the electron-bunch dynamics in magnetic bends has continued. We discovered that localized radiation and coulombic fields in the bunch have the potential to make important contributions to the transient bunch dynamics. Previously we had ignored these fields believing that they were negligible compared to the long-range influence of CSR. It turns out that this statement is true after long times, but the local fields can be more important on short, but still macroscopic, time scales. We are now upgrading our analytical and numerical analyses to include all of the local fields. The radiative transients have proved to be much more intricate than we originally suspected. The coulombic and radiative transients tend partially to offset one another; we are in the process of trying to formulate general qualitative predictions about these complex phenomena.

WBS 3 Cryomodule

Cryounit acceptance testing has been completed. Data reduction indicates optimum operating fields of 11MV/m and 9 MV/m for the first and second cavities respectively. The quality factor of the second cavity is depressed and will produce an additional 2 K heat load of 30 watts during operations at 9MV/m. The bridging cylinders order has been placed, finishing all bridging component procurement starts for the linac cryodmodule. The cavity pair beam line isolation valves and acceptance testing is complete, all valves have been accepted and waiting final dimensions from cavity interfaces. Four cavities have had final machining completed on interface flanges and are ready for final warm tuning. The intermediate beam tubes for these cavities are complete and dished head assemblies are in final fabrication.

WBS 2 Beam Physics

Much of the activity involving beam physics was focused on refining the design of the transport lattice in conjunction with measurements of magnetic field profiles in the prototype dipole magnet, and the design of the vacuum chamber to allow for installation of the array of electron-beam diagnostics in keeping with the impedance budget. By month's end, sufficient information was available to work toward freezing the top-level design drawing and the lattice. Plans are to include a design of the second recirculation arc that will facilitate a future upgrade to a 75 MeV machine to generate 1 micron light, as well as to add of order 1 m extra length >after the cryomodule to enable multipass monitoring that will facilitate machine operations. We anticipate freezing the design by mid-December, at which time we will institute a formal change-order process for proposed revisions. Such a process is already in effect for the diagnostic suite, and it is working smoothly.

WBS 4 Commissioning/Operations

WBS 4 -- IRFEL COMMISSIONING

Most of the activity centered on developing commissioning plans leading to first light. Commissioning plans were drafted for the injector from photocathode to injection-line dump, and the accelerator through the straight-ahead dump. A proposed FEL turn-on procedure was also drafted and is presently being discussed. As a result of these activities, there have been some changes to the diagnostic suite, to include addition of a few beam-position monitors, relocation of one of the multislit transverse-emittance diagnostics, and addition of synchrotron light ports to the optical chicanes. Additional considerations of commissioning for energy

recovery resulted in adding a cavity-based path-length monitor. The totality of these activities also led to further consideration of the dump-line designs. Only one dump-line design remains to be solidified, that of the energy-recovery dump, and the associated work is currently underway.

We decided to base the IR FEL machine protection system (MPS) on that of Argonne National Laboratory's Advanced Photon Source (APS). The APS system has been operating successfully for three years under EPICS, which is the control software used at Jefferson Lab.

A standardized set of IR FEL operating modes was tabulated, circulated, and posted on the WWW. The operating modes are compatible with present plans for the MPS. They also constitute a set of basic requirements for subsystems of the accelerator.

Facility

During this month the lower level of the building was completely enclosed with the completion of the 3' thick interlevel concrete pour. The fixes on the RF waveguide penetrations were completed and the walls around the interlevel were also finished. The interlevel surfaces were sealed and sand and rock fill begun in the interlevel areas. Filling was also done around most of the north and west of the building bringing the level up to ground level or above. This will aid in the insulation and drying of the concrete in the enclosure so painting can take place. Initial pours of the truck ramp were completed and the lobby/loading dock area excavated and leveled. HVAC installation was initiated.

Layouts of the cable tray and Jefferson Lab installed utilities were produced. A minor rework of lighting positions was sent to the contractor optimized for our current accelerator layout. The injector layout was redone to accommodate the new planned HV tank for the injector power supply. A layout which allows the easiest cryounit access was established. Rack layouts upstairs were finalized and layout drawings with rack and penetration identification were produced. Estimates were requested from several vendors for the new clean room. Communications plans were finalized for control between the CEBAF Machine Control Center and the FEL Facility. Work on the cable database was initiated and several WBS elements ordered their cables packages. Bids were solicited for commercial surveyor support during initial network generation.

Upcoming Meetings and Reviews

Maritime Technical Advisory Committee Meeting Dec. 17-18, 1996

Laser Processing Consortium Workshop Jan. 21-22, 1997

SPIE High Power Light Source Conference Feb. 8-14, 1997

DOE Basic Energy Science Review Feb. 24-25, 1997