MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IR FEL Weekly Report: August 26-30, 1996

Date: August 30, 1996

Management

- A detailed agenda was assembled for the LPC workshop to be held on Sept. 9-10th at Jefferson Lab. Following status reports on the Consortium and the FEL construction, a series of talks will be presented on laser-materials interactions in the IR. The working groups established in the January LPC meeting will continue their planning activities for User Lab fit-up and experiments.

Injector Test Stand

- Commissioning of the 500kV beam line for the Injector Test Stand continued. Using beam extracted from the GaAs photocathode with a HeNe drive laser, the transverse emittance measurement system was tested and the design dispersion for the magnetic spectrometer was verified. Switching to the doubled Nd:YLF (green) drive laser, the system successfully delivered a 22 microamp beam to the beam dump with the drive laser operated at a total power of 5mW at a 75MHz repetition rate. With the drive laser power increased to 0.65 watts, a 1mA average current beam was delivered to the dump. The peak charge per bunch was in the range of 25pC. With this successful test of all the beamline components and instrumentation, the gun assembly will be taken off line next week to change out the GaAs cathode. The present cathode has a crack and is misaligned but we were able to work around these problems by manipulation of the drive laser alignment.

- The first coupons of ion implanted alumina from LBL were tested as an alternative coating method for the new ceramic stack assembly for the ITS. New samples with higher implantation doses are expected next week. The new cathode support tube was completed and is ready for polishing.

Accelerator Systems

- Work continues on design of the 180 degree dipole at Northrop Grumman with completion expected to be per schedule. The prototype major dipole was assembled and the magnetic measurements test stand prepared to start tests. The design of the weak quadrupole was qualified by magnetic testing.

- The standard CEBAF klystrons were operated at 8kW average power for two days with no problems arising. The procurement cycle for a High Power Amplifier (HPA) that will allow operation of the IRFEL cryomodule at this increased power level was initiated.

FEL Systems

- Drawings for the optical cavity components are in internal review and check-off. A statement of work was drafted for CNU for the design of an interferometric cavity length measurement system.

Facility

- The scheduled date for pouring the final third of the FEL Building floor has been rescheduled to Sept. 2. Several non-conformances on placement of support columns and the pass-through culverts for the cryogenic lines had to be resolved prior to the final pour and start of the wall sections.