July 9, 1991 - Blue Sheet

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Project Progress Summary

July 30, 1991

FET Operations

  • A WBS 1 team spent one day investigating characteristics and causes for cavity window arc trips. A beam run was made with 23-microampere, 41.5-MeV CW beam for beam position monitor studies.

WBS 1

Facilities:

  • Moving the assembly of windows, HOMs, and warm beampipe to the Off-line clean room. Two new chem hoods have been installed.

Nb Pair Parts:

  • Electron-beam welded 24 seam welds on elbows, flanges on 30 elbows, and 30 fundamental power coupler extension waveguide bodies. The FPC documentation package is complete.
  • The CNC mill faced 30 elbow flanges and 24 seam weld preps. There is a capability to make parts for eight cavity pairs per month with 20% left over to do odd job requests. Twenty-four elbows received final flange finishing.
  • VTA cryogenics interlocks commissioning has begun.

RF Windows:

  • Parts are ready to send out to vendors once the procurement action is started to qualify vendors for brazing operations.
  • Ceramics were received from Insaco.
  • Pressure-reversal tests to induce cracks were done on five windows. They were done at 40 psi for ten times in each direction. No through leaks were seen. These windows will be thermal cycled and retested.

HOM Loads:

  • The 2 K leak checking of flanges status: in the final stage of modification of the vacuum system. More sensitive leak tests can be done by this week.
  • Four glassy carbon loads on copper flanges were tested on a cavity pair. No temperature dependence of absorption observed. The modes are damped to more than acceptable values and in a similar way in both cavities. The loads perform uniformly.
  • A draft change request is being prepared with Joe Bisognano for unheated loads. Checked three loads which were originally on CE001/CE002, which showed the worst Qext at 1970 MHz of any cavities tested (typically an order of magnitude worse than what is seen in 3000 psi material loads installed in other cavities). All three loads collapsed to an absorption of 1 db at this frequency. P. Kneisel assembled one cavity pair so loads could be interchanged. Measurements were taken with the loads interchanged and with the loads and elbows interchanged. Most modes were not affected by turning the heater on and off or by the load interchange. Some modes showed damping variations with different loads.
  • A vendor search is being made for electropolishing the HOM flange. We have the capability to do a short-term pre-production run for glassy carbon in-house.

Cavity/Cavity Pairs:

  • Machined a piece of the roll-over fixture so it is ready for the clean room. The alignment for the cavity pair fixture needs to square up the cavities to the fixture.
  • Disassembled IA001/IA005. This pair will be used for I. Campisi’s load switch tests. IA083/IA084 pair is ready for reprocessing. This pair will be used to finish cryomodule traveler #8.
  • The QA traveler rework is being done. The basic outline is finished.
  • I. Daniels has modified the tooling to allow tightening of the four bolts on the cavity pair near the RF window.
  • K. Saito reported on the results of his test for the Q disease using an electropolished cavity. This cavity had Fansteel niobium. The electropolished cavity showed no signs of Q disease.
  • Two RF window indium seals were tested with 40 mil wire indiums. The flange bolts were tightened to 35-inch pounds on the corners and 45-inch pounds elsewhere, which approximately halves the stress on the bolts and Belleville washers compared to the previous RF window flange configuration which used 60-mil indium wire. Then the indium seals were subjected to 10 thermal cycles between 300 and 2 K. The average leak rate is less than 3 x 10^-12 Torr liter/s. This low leak rate would allow the CEBAF accelerator to operate at least 10 years before it has to be warmed up to remove adsorbed helium from cavity surfaces.

Cryounit/Cryomodules:

  • One cavity pair is in the cryomodule assembly area being assembled to a set of end cans. This quarter-cryomodule will be used for the thermal cycle test and then as a spare.
  • The two other cavity pairs in the cryounit area are undergoing assembly. One is essentially complete and will be transferred over in the net week to mate up with cryomodule traveler #8. The other pair is being assembled into a cryostat.
  • Cryomodule traveler #8 has the return end can on.
  • A series of tests was conducted on the first cavity of Phoenix to determine if it preferentially arced at the windows. In seven hours of operation, six events occurred. All of these were in excess of 7 MV/m. A review of the log book will be conducted and additional tests will be performed next week on a better candidate.
  • Continued efforts to refine and resolve problems with the combined cavity-cryounit assembly fixture.
  • Continued progress in resolving window/HOM flange assembly procedures and techniques, and short- and long-term interlock instrumentation priorities.

WBS 2

Magnets:

  • The contract for the 108 sextupole magnets (SAs and SBs) was awarded to Everson Electric Co.
  • Laminations for all linac quadrupoles (QBs) and all extraction quadrupoles (QCs) have been completed and have passed dimensional inspection.
  • The die for the arc quadrupole (QA) laminations has been completed.
  • The proposals for the QA quadrupoles went to the “best and final offer” stage.
  • The proposals for the spreader/recombiner and dogleg dipoles were received and the evaluation process started.

Stands:

  • The first three of the 96 production dipoles stands for the east arc were received from Euclid Welding Co.
  • The first drawings of the first spreader stands started the checking process.

Vacuum

  • The 226 remaining dipole tubes were formed to the race track shape, were inspected and found to be well within dimensional tolerance, and were then shipped to the bending vendor.
  • The contract for east arc drift tubes was awarded to MKS/HPS Corp.
  • The request for quotation for the mezzanine for vacuum tube handling that is planned for the test lab was sent to vendors.

Cooling Systems:

  • McKenzie Construction Co. started installation of the LCW header in the linac service buildings.

WBS 3

  • Delivered two sets of control racks to the north linac for installation.
  • CPU board digital link communications problems under close scrutiny. We are working on several potential problem areas simultaneously. We expect to have the final solution in about two weeks.

WBS 4

  • A facility for the acceptance testing of the box power supplies is being assembled in the EEL building.
  • Assembly and testing continues with the trim system components. A total of fourteen trim systems have been installed: one in the injector service building, six in the north linac service building, and seven in the east arc service buildings.

WBS 5

Software:

  • Continued work in making RF controls more friendly.
  • Attempting to reduce TACL signal load.
  • Working with Hall C to adapt TACL for carriage control.
  • Database for tracking mode and fault reports has been put together.

Safety

  • All but two run/safe boxes are mounted.
  • All PLC racks are installed.
  • Five neutron channels have been ordered for the controlled area radiation monitors.

Diagnostics:

  • North linac and spreader viewer electronics and cables are installed and tested. East arc viewer documentation is complete.
  • North linac zones 1 and 27 BPM electronics and cables are installed.

WBS 6 – No report received.

WBS 7

  • Continuing the life test of the bellows seal valve.
  • CHL and the CTF operating in support of the FET and VTA testing.
  • The #3 water pump on the CHL cooling tower failed this week. Another pump was started; however, this caused the system to go down on low water flow. During the next shutdown WBS 8 has been requested to program the control computer to start the off pump if the water flow decreases to below 2000 GPM.
  • CVI has left the site. Discussions are in progress to determine when they will return. A date of CHL shutdown of 12 August still appears realistic.
  • Cryo and SRF continued VTA operations testing this past week.
  • A planned CTF shutdown to update and move the computer to the cryomodule control room on Monday, 29 July is in progress. Approximately a four-hour shutdown is anticipated, with luck. Everything that can be accomplished prior to the shutdown is being accomplished.

WBS 8

  • Continued working on third-lift Hall B wall sections. Only one roof our remains to be completed on the beam dump connector, and one roof pour on the beam-line tunnel for Hall B.
  • Continued installing shoring in Hall C to support placement of the concrete dome.
  • Backfilling continues in all areas when weather permit. Completed backfilling the ESR building and SB-4 areas, and they have been turned over to the Package B Contractor.
  • MCI, the end stations above-ground subcontractor, completed constructing the footings for SB-5.

Safety

  • The switchover to the new lock and tag system for the entire accelerator site is complete. Next, we will convert the test lab.
  • Patty Hunt will be focusing her activities in the SRF chemical safety areas. Inspection and evaluation of those area has begun.
  • Working conditions for the hot weather we are experiencing are being monitored by EH&S. Gatorade will be provided as conditions warrant. Supervisors will also be notified if conditions trigger ACGIH (American Conference of Governmental Industrial Hygienists) guidelines.

Support Services

Machine Shop:

  • Fabrication of 29 reactor coils for WBS 3 has begun.
  • Began fabrication of a prototype wire crimping tool is in process for Physics.

Stockroom:

  • Activity for the week: $25,823.18.
  • Activity for the month: $50,087.74.
  • Packaged and delivered electronic kits valued at $165,000 for WBS 3.
    • 345 RF converter kits
    • 345 analog board kits
    • 45 logic board kits
    • 21 CPU board kits
    • 21 I/O board kits

External Fabrication:

  • Quality inspected the fist article of the return line pedestal assembly at vendor site. Delivery this week (Sinclair).
  • Ordered remainder of the base plates for recirculatory magnet support assemblies (Sinclair).
  • Conducted a vendor site inspection of the HMS detector plates. Work proceeding well (WBS 6, Hall C).

CEBAF Summer Science Series

Lectures are being held in the auditorium at 3:30 each Friday this summer for teacher fellows, student interns, and other interested persons.

Future talks:

Aug. 2                  Data Acquisition and Scientific Computing                            Roy Whitney

Aug. 9                  Accelerators and the Future                                       Hermann Grunder

Special BEAMS Week

Don’t forget to sign your child up for the special BEAMS week, 19 to 22 August. The memo and sign-up form concerning the week has been circulated; if you did not receive it call ext. 7028. Deadline for sign-up is 7 August.