MEMORANDUM

To: J. Albertine, D. Helms, W. Skinner

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IRFEL Weekly Report Jan. 27-31, 1997

Date: January 31, 1997

Management

The December monthly report for the IR Demo project was completed and distributed on Jan. 29.

A laboratory-wide scheduling and resource planning effort was completed on Jan. 31 in order to resolve conflicts and optimize the use of the laboratory's design, fabrication and installation labor for support of the experimental halls and the IR Demo project over the next 12 months.

Grunder, Dylla, and Ware met the Under Secretary for Technology in the US Dept. of Commerce, Dr. Mary Good, at the Virginia Technology Summit held in Norfolk on January 29. Dr. Good, whose oversight includes the NIST laboratories, encouraged us to ask potential users of our FEL facility to submit proposals to NIST's Advanced Technology Program.

Injector Test Stand

We completed baking the gun and beamline. Plans are to make the photocathode today (31 Jan 97). The harp and viewer equipment were installed, and magnet installation has started. Tasks that remain are to attach the SF_6 tank and align the laser-steering mirror on the light box leading to the photocathode. We are on track to turn on the electron beam next week.

Regarding upgrading the photocathode gun:

Coated Cathode-Support Tube - FM Technologies is sole-sourcing the multilayer coating of the tube instead of sequentially contracting for each layer. They forecast that acceptance tests of the samples from the sole source will be complete today. If the results are satisfactory, delivery will be within the next two weeks.

Ion-Implanted Ceramics - This week Lawrence Berkeley Lab had to satisfy a number of their other implantation customers and refurbish their electronics to increase the efficiency of their implanter. Implantation of our first ceramic should begin on Monday, 3 Feb., and be completed by the end of the week.

A new supply of 1/4-inch-diameter platinum rods is required to complete the implantation of the second improved ceramic. Procuring the platinum rods from an external source would take an unacceptable 4 weeks. We plan instead to make our own rod, and project completion by Wednesday, 5 Feb. The necessary materials are in hand.

Cr/V-Oxide-Coated Ceramics - In view of LBL's success, we plan to remove the Cr/V-oxide coatings with the unacceptably high resistances on the three other ceramics and substitute the ion- implanted surface.

Regarding other ITS activities:

We received the third Svetlana klystron this week. It is a spare klystron for the FEL injector. Svetlana claims to have operated this klystron to 85 kW cw prior to shipping it. We will try to duplicate their results as part of our acceptance testing.

Regarding the beam-transport system:

The design drawings for the optical-chicane dipoles were modified to incorporate a wider configuration that provides the extra width needed for good end field drop-off. We are in the process of looking at the design of the entire optical chicane and optical-cavity mirror to make sure there are no hardware interferences. We plan to initiate procurement of the optical-chicane magnets based on the existing drawings, and then follow up with signed-off versions that will include any necessary corrections.

The design of the reverse-bend dipoles and the 180-degree dipoles continued at Northrop Grumman.

The method for phasing the beam at 42 MeV using the injection/extraction dipoles was finalized, which in turn has led to firm guidelines for the designs of these magnets. In the extraction chicane, the first wedge dipole will have an extra 150-turn coil that will permit bending the 42 MeV beam. The third dipole in the chicane (a mirror image of the first) will be made of the same iron as the first dipole, but without the extra coil. Hysteresis differences between the magnets after phasing will be zeroed out by using the a reversing switch to allow the power supply to zero the remnant field. Similar wedge magnets in the injection chicane will be made in the identical mechanical configuration, but less wide, thus retaining a need for a third style of magnet.

Fabrication of the quadrupoles for transporting the beam along the back leg of the recirculation loop progressed as the first four quadrants of laminations were made and 10 coils were potted. The first article is slated to be shipped to us by air next week.

Regarding cryomodule fabrication:

Two ceramic warm-window assemblies are due to be completed today (31 Jan 97). The upgrade of the ring-resonator test stand to improve its vacuum is also due to be finished today. Testing of the new warm windows in the refurbished test stand is slated for early next week. In addition, assembly of the first cavity pair for the cryomodule is scheduled to be completed next Tuesday.

Regarding electron-beam diagnostics:

Fabrication of the modified prototype stripline beam-position monitor (BPM) was successfully completed. This BPM also successfully passed its electrical acceptance tests.

We have a flange-mounted design for the button BPMs that are envisioned for the centers of the 180-degree bends. This provides flexibility in that we have the option to install a blank-off flange and use the co-located optical-transition-radiation viewers to monitor beam position at these locations during commissioning. Having the BPMs on hand would provide redundancy and the possibility to incorporate autosteering in the future. The design enables change-out to be completed within one day.

Twelve of 52 slit arrays have been successfully fabricated for the multislit transverse-emittance diagnostic. All of these arrays should be complete within the next two weeks.

A prototype diffraction-transition-radiation (DTR) detector has been installed on the nuclear- physics machine for experimentation next week. If successful, DTR detectors will then be used at various synchrotron light ports along the FEL to nonintrusively monitor the bunch length.

We received the video-over-fiber distribution system which will be used to operate the FEL remotely from the Machine Control Center (MCC). This system will provide 14 channels of real- time video between the FEL Facility and the MCC.

The "to-build" vacuum-controls drawing is finished, and the magnet-controls drawings are being updated.

FEL Systems

Wiggler

Purchase requisitions for components of the wiggler support were prepared. The designs of the vacuum chamber and chamber support are progressing nicely at Northrop Grumman. Vacuum-chamber drawings are now ready for checking.

Optics

Design efforts this week were focused on investigating potential interferences between the new optical chicane dipoles and the optical cavity assemblies. Changes to the design of the diagnostic pick off and mirror cans are being incorporated into the drawings. The sensitivity of an intensified CCD camera was measured, and it and other cameras that will be used in the FEL accelerator area have been moved to the main accelerator for tests of their survivability to radiation. The optical transport system mirrors were ordered, along with other parts for the optical cavity assemblies, specifically the custom crosses and some fasteners.

For the ITS, we received the redesigned divide-by-two EO modulator, and we are installing it into the drive laser for tests. We also successfully tested the software for remote control of the laser pulse selection hardware.

Operations/Commissioning

Candidates for charge-coupled-device (CCD) cameras have been identified for use in conjunction with synchrotron-light monitors. One outstanding question is their robustness in a radiation environment. Plans are soon to install and monitor a camera in the nuclear-physics injector to get an indication of its lifetime.

As described above under "Accelerator Systems", the method for phasing the beam at 42 MeV using the injection/extraction dipoles was finalized.

General plans were considered for timing the commissioning of the energy-recovery loop vis-a-vis obtaining first light. At this time, we are planning to commission the hardware along the recirculation loop in parallel to achieving first light, and afterward, to commission fully the process of energy recovery.

Facility

To date we have received only one bid for the clean room for the FEL Facility. We are reviewing the proposal and are continuing to solicit bids from other vendors.

The high-voltage-power-supply tank for the FEL Facility needed some redesign to accommodate elliptical heads rather than the hemispherical heads proposed in the initial design. The redesign was done and sent to the potential vendors.

Regarding Facility construction, the pad for the main power transformer was poured, and the transformer was set in place. A retaining wall remains to be poured for the power-distribution pad and the pad for the HVAC heat exchanger. A substantial amount of steel framing was craned to the second floor, as were two power distribution units. Survey teams were surveying the building network throughout the week. Utility piping was welded in place along the north wall. Lighting fixtures are 90% complete in the lower level.

An installation-coordination meeting was held to schedule the next wave of Jefferson Lab activity. Coming up will be installation of cable trays, cryopiping placement, and blocking out the positions of the magnet stands.