MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IRFEL Weekly Report, September 15-19, 1997

Date: September 19, 1997

Management

Installation and subsystem commissioning activities proceeded this week at a rapid rate. Highlights include: installation of all eight of the optical chicane magnets, successful testing of 50kW and buncher FR systems, and installaiton of all of the required DC power supplies.

Jefferson Laboratory's annual Science and Technology Review was held this week (Sept. 17-19) as a required component of SURA's contract with DOE to operate the laboratory. Two members of the seven person review committee focused on the FEL program. Good marks were received on the execution of IR Demo construction project, including resolution of issues that were identified at the mid-project DOE review in February. The recent attention given by the FEL Program Management was encouraged to continue to develop basic science applications which complement the existing industrial and Navy applications.

An agenda for the Oct. 2-3 IR Demo construction project close-out meeting was forwarded to Navy High Energy office and DOE Site Office.

On Tuesday, Tony Favale and Alan Todd from Northrop Grumman visited the laboratory to discuss continuation of our collaborative R&D activities for next year.

Accelerator Systems

Regarding the beam-transport system:

The optical chicane dipoles were installed and fit well around their vacuum chambers. The Injection/Extraction dipoles are going through hall probe measurement where field clamps are adjusted to bring all units within the required field integral. Bore gage readings revealed that two DUs have poles with variation in the mu metal/brass/adhesive thickness at .003 inch, greater than the specified .002. We arranged for a re-glue by Everson.

Tom Schultheiss from Northrop Grumman constructed a magnetic model in TOSCA of the DV dipole and the 10 MeV line that is adjacent to it. At week's end, the model was working, but not verified with data from magnet measurements. Robin Wines took over the use of the model and of finding a solution to shielding the 10 MeV beam line while still providing uniform field integrals through the good field region.

Everson has started final assembly of the four DX style reverse bends and completed gluing the mu metal and brass on pole tips for two of four of the other style of reverse bends, the DQs.

Everson also received the contract to assemble the 180 Degree Dipoles (DYs) this week. The agreement contains a provision to prove out the process of gluing segmented mu metal and brass using bolts and the pole slabs themselves. The time devoted to this development will retard the final assembly of the last 180 degree dipole until mid November.

Progress in finishing the system is also being restricted in the magnet measurement area. It remains full occupied in measuring DU/DV dipoles. We will continue to advance the assembly of the entire beam transport system in the arcs by an arrangement with Everson, postponing the final assembly of the DQ reverse bends and substituting a trial assembly of the parts for the second 180 degree dipole. It will have filler pieces substituted for the mu metal/brass. We will install this trial assembly magnet as well as two of the unmeasured DX dipoles and the pole tips from a DX and a DQ (poles that were machined by the vendor as production spares) onto their respective stands in the first arc. This assemblage is a base on which we can fit-up the entire seven or eight segments of the vacuum chambers for the two arcs before final cleaning. There are no bellows between segments and such a fit-up will be invaluable for smooth final assembly. Everson will continue final assembly of the DQ and assembly of the first 180 Degree Dipole in parallel with the chamber fit-up. George Biallas visited Everson on Friday.

In the quadrupole and sextupole area, winding of coils and machining cores for the eight Panofsky trim quads continued at Magnet Enterprises International (MEI).

In the corrector area, manufacture of the coils for the phasing dipoles (DGs) continued at MEI. Contrary to what had been reported earlier, the manufacture of their mu metal cores was not started. The contract was delayed by arm wrestling over fine points associated with this sole source procurement. Fabrication of coils for the reverse bend correctors continued at Advance Magnet Lab (AML).

The air core corrector contract was awarded to AML with first articles promised in two weeks and the final delivery slated for 8 weeks ARO. Manufacture of the to prototypes needed for the injector line continued with all coils wound and potting ready to begin.

The chambers for the first of four reverse bends are complete and are awaiting completion of the cross for the beam scraper to be bolted together. Welding of ends on to bodies continues on the remaining reverse bend chambers. Welding on the 180 degree chambers started at Master Machine, anticipating delivery around Sept. 29.

Two power supplies for the injection and extraction dipoles were installed in their racks, completing installation of the required inventory of DC power supplies for the system.

Regarding RF systems:

The two 50 kW klystrons were operated without difficulty in the FEL Facility, one to 45 kW and the other to 55 kW. In addition, the buncher cavity was powered to its full-rated value of 2.5 kW.

Preparations for turning on the photocathode gun proceeded in earnest throughout the week. Testing of its high-voltage power supply gun was completed from the FEL Facility control room. Fit-up of the vacuum tank and elbow that connects the gun to the high-voltage stack was also completed today (19 Sep 97). An additional 1" spacer was needed and will be available Monday morning; our Machine Shop will make it by cutting a hole in an existing blank-off flange.

Regarding instrumentation and control systems:

Major activities center around preparation for high voltage conditioning of the gun and injector beam next week. The controls interface for operating the high voltage power supply from the control room are complete. The voltage and current readbacks are connected through EPICS as well as being patched to the table top. These signals are also available on the projector for ease of viewing. The laser shutter control is also being worked.

The Personnel Safety System was recertified this week, one last step is to connect to the gun high voltage power supply for gun conditioning early next week. This system is fully operational from the Accelerator Main Control Room.

The trim magnets are connected and ready for the injector beam line, the balance continue to be connected. The vacuum system is also staying ahead of the installation activities. As the beam line is evacuated, the ion pumps can be brought on line. The EPICS vacuum control screens may be ready next week.

The HP workstations are being setup in the control room and user labs. The server conversion will happen on Monday; the injector test stand server will be decommisioned and the entire load will be on FEL1 and FEL2.

The (prototype) VME buffer board for the video multiplexing system is complete and documented. This is now being used to commission the EPICS software and control screens. The initial beam test do not require the mux but it may be ready.

Documentation, cable, parts, & boards continue to arrive for the Analog Monitoring System (AMS). The mux is identical to the video system so it's making great progress as well.

The work in Hall B is finishing up so the personnel has returned to complete OTR foil assemblies, and viewer installation. The BPM cabling and electronics installation continues to move ahead.

FEL Systems

Injector Reinstallation

The gun bake was completed successfully and hookup of the beamline elements is started. The high voltage tank was mounted on the gun. The high voltage supply was tested to 350 kV in 14 PSI of instrument air. It is now being fitted up to the gun. The supply can now be controlled and monitored from the FEL control room. The final stand for the optical transport was received and installed. The last two mirror cans were installed and aligned.

Wiggler

All the flanges were welded on the wiggler vacuum chamber. The chamber is ready for leak check and, if necessary, straightening. It will be fitted up to its support next week.

Optics

Components for the mirror cassettes were awarded this week. Components for the bodies went to Master Machine. The linear stages that go in the mirror cassettes was also awarded. The last mirror cans have been hung with modifications made to make them fit. Beam should be delivered to the light box next week. Modifications to the clean room chilled water system are also being made.

Commissioning/Operations

A draft of the complete injector setup procedure is now available and is posted on the www at http://www.jlab.org/~legg/procedures/Injector_setup_proc.pdf. We will be refining it over the next two weeks. In addition, the Magnet Performance Integration Plan is published as a Jefferson Lab technical note, TN-97-034. It, too, can be viewed on the www at the technote page of www.jlab.org/~douglas.

Detailed analysis of the longitudinal emittance data from the 350 kV gun experiments conducted over the last weeks of the Injector Test Stand Program is now essentially complete. The analysis strongly suggests that there was an error in the measurement of the bunch charge for the long pulse, high current setup. Specifically, simulation (PARMELA) results closely match the phase-space data if the input bunch charge is 175 pC rather than the 135 pC measured with the picoammeters. Accordingly, we will pay special attention to bunch charge measurements as we commission and operate the gun in the FEL Facility. It is difficult to infer a precise value for the rms longitudinal emittance in the ITS experiments because the measurement is dominated by uncertainties caused by finite slit size. However, an upper bound is 44 keV-deg at 175 pC bunch charge, which compares favorably with the 50 keV-deg required at the wiggler, although if the upper bound is close to the real value, there is little margin. Nevertheless, all indications are that gun operations at 350 kV produce an electron beam with phase-space properties that meet requirements.