FEL Upgrade Project Weekly Brief
June 19-23, 2000


This week we hosted the Laser Processing/FEL Users workshop. Approximately 70 attendees heard briefings on the FEL Upgrade project, the results of the March 2000 user run and the plans for the next user run which begins on Monday June 26.


Management attention this week focussed on hosting the Laser Processing Consortium Workshop, analyzing the current FEL cost book to identify a scope cut of $276k to defray the costs of a DOE "work-for-others" tax on the upgrade project, and preparations for the upcoming FEL user run.

Design/Construction Activities

Beam Physics (WBS 3): the documentation for Rev.1 of the upgrade accelerator driver lattice was completed and posted on the web at www.jlab.org/~douglas/FELupgrade/masterindex.html.  Injector (WBS 4): preparations are being made for baking out the apertured cesiator. All preparations are in place for ion implantation of the spare ceramics for the high voltage stack in the gun assembly at LBL.

SRF (WBS 5): P. Kneisel returned from a visit to KEK/Japan where he investigated KEK's use of electropolishing for producing high gradient SRF cavities. As presented at the project kick off meeting, we are considering the option of using electropolishing as an alternative to the present buffered chemical polish (BCP) depending on the results of a test with multi-cell cavities.

RF Systems (WBS 6): Glassman, Inc has made recommendations on their concerns for doubling the current capacity (from 5 mA to 10 mA) for the gun power supply. R. Walker will be analyzing their concern for possible out of specification voltage distribution across the high voltage assembly.  The HPEE group is making preparations for installing waveguide in the 3rd cryomodule position through the FEL ceiling penetrations during one of the weekend shut downs during the upcoming user run.

Beam Transport (WBS 10): we have obtained two bids on the large order (80 tons) of type 1006 steel we will need to fabricate the upgrade dipoles. However, we may consider procuring several smaller slabs from a specialty steel manufacturer before we order the large heat in order to roughly size the slabs we need. The drawing for the cores for the quadrupoles is in for QC. We have started some preliminary lay-out for stands and have begun testing of the magnetic properties of the steel we will use for the dipole vacuum chambers. For our design of the large dipole magnets we plan to take our existing model of dipole magnets and transform to the new larger size.

Wiggler (WBS 10):  the drawings for the wiggler dispersion section hardware are almost complete.

Optics (WBS 11): we have begun the preliminary lay-out of the R5 mechanical design. We have reviewed the analysis supplied to us by AES of the conceptual mirror cooling configuration that was jointly designed with AES and are ready to proceed with the next design step.


This was a hot check out week for the IR Demo in order to fully prepare the machine for user operations which begin on next Monday (June 26) and continue until August 4. Early in the week we attempted to bring the machine on line at 5 microns with a new laser spot on the photocathode that overlapped a high QE region. Unfortunately, this spot produced some beam halo that could not be sufficiently cleaned-up for cw operation above 1.4 mA. We moved the laser back to our traditional operating spot and achieved kilowatt operation at 3 microns in preparation for the first PLD (pulsed laser deposition) experiments on Monday which have requested high power operation at this wavelength.  For the upgraded injector we plan to eliminate the obstructions in present light box which prevent us from using larger areas of the photocathode. Today we also completed re-certification of the Laser Safety System (LSS) prior to operations.

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