FEL Upgrade Project Weekly Brief
August 26 September 1, 2000


An initial planning meeting was held to coordinate installation schedules with other activities at the lab.  Initial cuts at the
installation logic and possible scheduling were established for review and comment.  A number of possible cross linkages were identified and the installation groups got action items to study the plan and identify possible ways to alleviate schedule crunches and eliminate interferences during this busy time.

Design/Construction Activities:

Beam Physics (WBS 3.0):

Preliminary estimates of the effect of CSR in the Upgrade were published as JLAB-TN-00-017, available on-line at http://www.jlab.org/~douglas/FELupgrade/technote/JLABTN00017.pdf .  Ongoing study of longitudinal phase space management issues suggested  that very short pulse production (<100 fsec fwhm) may be possible.  Implications on transport system specifications (CSR, power supply and energy stability) are under investigation.  Work began on generalization of the optics model for SRF cavities, so as to simulate the focussing effects of the 7-cell module properly.

SRF (WBS 5):

We scheduled vendor visits to start helium vessel fabrication for 5 September.  Likewise spaceframe and vacuum vessel visits were scheduled for 18 September.  End can and waveguide procurements are now underway.  The cavity half-cell mechanical and rf characterization is being performed prior to welding.  The next two cavity blanks have been machined and are ready for cell pressing.

RF Systems (WBS 6):

The Design Review for the 100 kW klystrons was held this week.  It was a very good meeting with no problems being found.  The vendor is designing a very robust klystron with significant margins for all aspects.  They are on schedule.

The RF installation of zones 3 & 4 continue.  This effort is ahead of schedule.

The acceptance tests for the spare 50 kW klystron was completed this week.  It is the best klystron we have received from Svetlana.  It was out of specification for only the heater volts which we can accommodate with our heater power supply.

The specification for the upgraded power supplies for the 100 kW klystrons is in final draft form. It will be released next week.

Instrumentation (WBS 8):

The new 3" design for the BPM has passed the RF testing and is back in the shop to have the end plate and flanges welded on.  The flanges were changed from the original 6" to 4 5/8" (standard flange for 3" beam tube); these are less expensive and will more readily accommodate the air core trim magnets fitting over top.  The change that allowed the smaller flanges is using studs with nuts on either side instead of bolts.  The initial girder assembly will be done in the test lab so the studs will not be an issue.  The bid packages for the BPMs and beam viewers are being sent out now, the final numbers are 30 - 3" BPMs for the IR, and 26 - 3" shielded beam viewers for the IR.  The Kaman RF feedthrus will be purchased by JLab and sent to the machine shop
manufacturing the BPMs.  All of the viewer sub-assemblies will be purchased by the manufacturer.

Designs are progressing for a 32-channel sample and hold VME card.  This will only use power from the VME crate and output to a VMIC MVME3113A 64 channel A/D (12 bit) digitizer.  The A/D is used on site so the software is already available, the sample and hold only requires a beam sync trigger and can deliver a 12 bit sampled value for about $50 per channel.  The four channel S/H with re-settable integrator was tested and will be installed for current (charge totaling) and laser power monitoring.  This design and PC board was completed this last spring but not commissioned.  An additional feature was added to this design; the delay which normally samples at 110 microseconds into the macropulse is now connected to EPICS so that when the macropulse is 100 microsecond or less the hold point is moved back to 9.5 microseconds.  This will allow both electron current and laser power to be monitored at any pulse structure.

A new VME design for Machine Protection System (MPS) inputs is also being worked on.  This will convert DC level to the 5 MHz fiber optic output which the MPS uses as a standard.  This board will be used in the future for many of the optical transport "warning" inputs.

Interviews were conducted for the electronic tech position; one of the four was a qualified candidate.  A number of drawings from existing equipment were gone over, marked-up, and returned to document control.  This activity is an ongoing effort to ensure accurate documentation of the instrumentation and controls systems.

Beam Transport (WBS 9):

We continued layout of the GX Prototype.  The 3D CAD model is now ready to start detail drawings.  In the analysis of 3D magnetic model of the GX we are still trying to refine to nubbins on the pole edges to widen the good field region.

Five coils are wound and qualified and cooling plates are being added.  The machining of the core prototype quadrant will start Sept. 5.  The trial pole face piece was measured and found to be true to the theoretical curve to less than 0.001 inch.  Success.

The report of the Technical Evaluation Team for the engineering service contract was completed and the competitive range was determined.

A meeting was held with the engineering group to iron out the sequence of installation.

Wiggler (WBS 10):

Optical Klystron
Manifold fabrication has started.

Dispersion Section
We are working in the specifications and requisition to get the unit fabricated.

Optics (WBS 11):

This week's efforts were devoted partly to preparing for a half day "optics retreat", where we reviewed the status of the optical
subsystems, and partly to preparations for the brief operations period occurring the second week of September.

Components for the upgrade continue to come in, specifically, we received the 4.5" diameter calcium fluoride windows for the optical beam position monitoring system (O-BPM).  We also received an upgrade to Paraxia, the other optics-modeling software package we use.

Optical Cavity component conceptual designs were reviewed and internally critiqued.  Approaches were chosen for several of the metrology systems required to operate the R5 cavity.  Layout of the system was discussed and the compatibility with the current beamline layout confirmed.  Analysis of the near concentric resonator approach using "best available" coating technology and use of deformable and controlled focal length mirrors was presented and limitations discussed.  A key point discovered was that at these low coating absorptions the intrinsic absorption of the transmissive substrate becomes the limiting factor.  Suitable substrates are not available at all wavelengths.  This discussion is to be continued at next week's meeting.

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