MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IR Demo Project Weekly Report, December 15-19, 1997

Date: December 19, 1997

Management

Highlights for the week include: (1) completion of the replacement of the vacuum isolation valves on the linac cryomodule and cooldown of the module to 2K; (2) placement of the beamline from the exit of the cryomodule to the tune-up dump under vacuum; (3) restart of beam commissioning activities; and (4) sign-off and release of the reverse bend dipole magnets (DQ) from magnetic measurements.

The project monthly report for November 1997 was completed and distributed to the DOE and Navy Program Offices.

The preliminary agenda for the Jan.14-15th LPC Workshop was prepared and distributed to the consortium mailing list.

On Monday, Dec.15, F.Dylla, accompanied by W.Lundy and C.Moore of NASA-Langley Research Center, gave a joint briefing to the NASA Chief Technologist, Sam Venneri, at NASA Headquarters in Washington concerning NASA's potential interest in using the IR Demo User Facility. Venneri suggested that several NASA Centers should have an interest in using the FEL for NASA-related activities including: JPL for microfabrication R&D, NASA-Lewis for advanced coatings development; and NASA-Langley for R&D on materials and polymers. He asked that a capabilities/facilities use document for the IR Demo Facility be forwarded to the above NASA Centers.

Commissioning

We began beam commissioning activities at 14:30 yesterday (12/18), not surprisingly went through a few hiccups in the process of turning on the injector, and by 0800 had beam at the viewer immediately preceding the cryomodule after running it through the injection line with both cavities crested. Beamline parameters from the November runs seemed to work well, indicating consistent machine performance.

This morning (12/19), checkout of the vacuum-interlock system through the cryomodule down to the straight-ahead dump is proceeding. Open questions at this writing (1100 Friday) include whether to reset the vacuum-valve trip limits in the vicinity of the optical cavity, and if so, to what values, and how to configure software controlling the rf interlock to the drive laser so it does not needlessly shut down. Both are being worked this morning.

Plans are to take beam through the cryomodule today and do transient phasing tonight. Then tomorrow we take beam through the optical chicane and crest the cryomodule cavities. D. Douglas suggested we consider taking the beam all the way to the straight-ahead-dump viewer and then crest, a process that he thought would be straightforward based on experience with CEBAF. We will consider this idea.

J. Preble reported that the cryomodule's performance after thermal cycling for replacement of the troublesome valves appears unchanged. Gradients for all of the cavities are consistent with earlier measurements, as are the unloaded Q's of the entrance and exit cavities. On the other hand, the static heat load rose, raising the error bars in the Q measurements. The source of the increased heat load is not yet identified. Bottom line is that all indications are that we still have a 47 MV cryomodule.

Installation Activities

The SRF group installed 2 VAT valves on the cryomodule and pumped it down to 2°K this week. It appears the cryomodule handled the thermal cycle without cavity gradient or Q degradation, but with a heat load increase.

The installation of all magnets, diagnostics, and vacuum equipment for the machine through the 2G, straight ahead dump, were made and appropriately shielded for operations.

The RF cryo heater control code was tested this week under load resistors. It is ready to test under RF operations. A software bug to download the external RF coefficients was found and solved this week. Additional work is being done to separate the Injector RF modules into individual systems and make the overall Injector more robust.

The 4 DQ magnets have been measured, signed off, and are available for installation in January.

The last DV magnet had its field clamps adjusted so that it now meets the field flatness specification, but it will be tweaked next week to improve its effective length.