MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IRFEL Weekly Report Sept. 16-20, 1996

Date: September 20, 1996

Management

Plans are completed for next week's MW Workshop which will be hosted by the Laboratory on Sept. 24-25th. We expect approximately 35 attendees from outside organizations. The workshop was organized by Alan Todd of Northrop Grumman.

The August monthly report for the IR FEL Demo project was forwarded to the Navy and DOE on Sept. 20. The first installation planning meeting was held on Sept. 20 with WBS managers and representatives from the installation teams to begin coordination of the installation tasks in the FEL building. Detailed lists of tasks and labor estimates are being reviewed with the goal of optimizing the use of labor and minimizing the conflicts with the support of the CEBAF accelerator operations.

A design review for the optical cavity is scheduled for next week on Sept. 26

Injector Test Stand

- Injector commissioning activities included the following:

1) We fully inserted the cathode into the gun and were able to run

with laser light being extracted from the analyzing port.

2) We remeasured the photocathode quantum efficiency after one week and measured 3.2%. This is down from 5.6% measured Monday.

3) We had problems with a small vacuum leak in the lightbox which subsequently sealed itself. To better coordinate subsequent activities in the ITS and avoid potential disruptions of the run schedule. a work permit system has been instituted.

4) Problems which appeared in the drive laser's ability to deliver high power were potentially attributed to a suspected problem with the heater unit for the SHG crystal which should be rectified with a replacement available next week from the manufacturer.

5) Optical-path alignment was completed to a point at which beam operations could proceed. More measurements on the surrogate system are still needed for system signoff.

- The rf interlock for the drive laser was installed and checked out. This interlock is designed to prevent rf-induced Q-switching of the laser, and thereby solves the problem that lead to damaging a doubling crystal during the week of 19 August.

- The buncher cavity and its water skid are now installed in the test cave, and its Temporary Operational Safety Procedure is signed off. Soon we will test the buncher at power.

- Fabrication of the cryounit progressed to the point of installing the end cans, i.e., closing up its cryostat.

Accelerator Systems

- All of the hardware tests associated with cryomodule-klystron operation at 8 kW have been successfully completed. Plans are to provide this capability for first light provided we can procure the necessary power supply in time. Specifications for the power supply have been developed and submitted to our procurement office for dissemination to potential vendors. Negotiation with vendors will commence shortly.

- An analysis was initiated to explore whether higher-power klystrons might significantly ease the rf-control requirements and procedures for the cryomodule in the presence of energy recovery.

- The design of the multislit aperture (for transverse emittance measurements of the 10 MeV electron beam) and its mounting is essentially complete.

- Specifications and costs of bridging components for the cryomodule's cryostat are being iterated with potential vendors in an effort to keep costs down.

FEL Systems

Wiggler

A successful review of the mechanical design for the IR wiggler was held last week (Sept. 13) at the vendor (STI). Final drawings for fabrication approval should be shipped to us next week.

Optics

Material was prepared for next week's review of the optical cavity on Sept. 26. Modeling efforts are continuing for the thermal distortion of the mirror substrates using both sapphire and silicon substrates. Support labor was provided to support ITS operations noted above.

Operations/Commissioning

Considerable progress has been made on the "10 MeV set-up procedure" for the FEL injector and its dump line. A bulletized version of the procedure will soon be posted to WWW.

Facility

Concrete was poured this week in the injector pit area and part of the ceiling in the West end of the building. We provided the contractor with a signed drawings indicating all penetrations for FEL related utilities and hardware.