MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IR Demo Project Weekly Report, October 27-31, 1997

Date: October 31, 1997

Management

Dr. Eli Zimet from ONR and Joung Cook from NRL visited the laboratory on Friday Oct. 31 to review progress on the FEL project and discuss future interactions with the Navy. The visit was very valuable in gauging the Navy's interest in both FEL technology and the use of the FEL User Facility for laser-material studies.

Jefferson Lab's FEL program was a co-sponsor of this week's workshop on "The Scientific Applications of 4th Generation Light Sources, which was held at the Advanced Photon Source on Oct. 27-29th. The IR Demo and its User Facility were prominently mentioned in overview talks on FEL technology development and in working groups discussing applications of high power IR and UV light to materials physics and chemistry. Even though the 4th Generation Light Source is usually a term reserved for an x-ray source with a considerably higher brightness (x 10e4) than the present 3rd generation sources (like APS, ESRF and Spring-8), the workshop broadened the definition to include the full spectrum from IR through DUV to x-rays, in view of the fact that a linac-driven FEL could provide the brightness advantage across this full spectrum. To reinforce this broader definition of 4th generation sources, we were able to attract five of the users of the IR Demo to the workshop to give presentations during the scientific application working sessions. The final product of the workshop will be a white paper outlining a research plan for the development of 4th generation sources and a summary of scientific applications in materials, chemistry, biology and atomic physics.

Installation Activities

The injection line from photogun assembly to injector dump is now fully installed and ready for commissioning activities. All components for the drive laser assembly and drive laser transport have been completely installed, aligned and tested for operation. The injection line dump shielding has been put in place.

A corrector magnet in the injection line (which is not needed for initial commissioning and can be removed and replaced without interruption of the vacuum) was removed for measurements in the magnet test area. These measurements will be useful for us to provide to the vendor responsible for completing the remaining corrector magnets for the accelerator.

The optical chicane vacuum chambers have been replaced after they were removed for a minor modification needed for fit-up of BPM assemblies. Final assembly of the wiggler vacuum chamber within its supporting frame was completed this week. Assembly of the clean hoods which will be placed over the optical cavity assemblies proceeded this week prior to next week's planned installation of the optical cavities.

Commissioning Activities

We ran beam at 350 kV from the gun through the buncher cavity to a viewer assembly just upstream of the injector cryounit. The buncher was operated at its nominal power loading of 2 kW. The drive laser in its final configuration ran to the required level of performance in these tests.

RF commissioning of the injector cryounit began this week. The exit cavity was operated at gradients of approximately 9.5 MV/m until problems with waveguide guard vacuum faults were noted. SRF commissioning activities were halted and leak test operations were begun. On Thursday, leaks were found at the interface seal for the warm window. The cryounit was then warmed up to allow the warm window assemblies to be removed and the new seals installed. We plan to cooldown the cryounit on next Tuesday, which is a scheduled maintenance day for the CEBAF accelerator. (This minimizes the effect of any small probability transients that the cool-down may impart on the 2K cooling system.)