Minutes of IR FEL Mechanical Systems Meeting, March 21, 1996

NOTE: Meetings are held every THURSDAY, 1:00 PM IN (BLDG. 58), TEST LAB CONFERENCE ROOM, unless otherwise notified.

ATTENDEES: S. Benson, G. Biallas, C. Bohn, L. Harwood, K. Jordan, D. Kashy, D. Kehne, L. Merminga, C. Murray, G. Neil, J. Parkinson, J. Preble, C. Rode, J. Susta, M. Wiseman

Decisions/Comments:

G. Biallas announced that to meet the budget goals for the project; he had to simplify the design of the vacuum system, removing valves, bellows and flanges. The machine will have to be welded in situ in some instances. The magnets also required simplification. He will no longer put in coils that can be used at 100 MeV. If any of these tasks becomes more complex than he envisions, we will have to have a change request and get money out of contingency.

Preliminary calculation of the impedance of the vacuum chamber indicates that the total impedance is in the order of 150 V/pC with the cavities dominating at 110 V/pC. Preliminary budget was about 1000 V/pC. Consequently, extraordinary measures at maintaining the vacuum tube environment may not be necessary. For example, the slots in the shielded beam viewer need not be micro small or a screen may be just as good as long as they expose a 2 sq. inch area. These calculations are very rough and preliminary; they refer to the "old" drawing with the wiggler between the bends, and they do not accurately incorporate the bunch-length profile vs. position in the machine. B. Yunn will be refining the impedance estimates as we progress.

Surplus Power Supplies for the magnets may be available by January of '87 and that could extend to July of '97. They have a nominal value of 220 A. max. and are owned by C. Rode.

Action Items:

G. Biallas/J. Parkinson - Do the appropriate calculations and get Sign-off on relaxed vacuum requirements near cryomodule by R. Sundelin & P. Kneisel. We need the hard interlock values for closing valves. No progress.

D. Douglas - Add the bunch lengths to zones on the layout drawing so impedance issues can be assessed. No progress.

J. Bisognano/B. Yunn - Make a list of impedance issues and begin analyses. Known issues discussed to date include impedances of the crotch chambers associated with the wiggler, and vacuum-pipe transitions. Some progress. B. Yunn appealed for references on the Cookie Cutter design because the ABC code doesn't provide good results.

H. Liu/D. Douglas - Resolve effective length vs. actual length ratios in the injector dipoles.

K. Jordan - Resolve the question of whether we need a 5th OTR in the Wiggler region.

J. C Denard - Calculate from the Hall C data how much scatter the BPMs can take. Scheduled for after the review.

J. Kraft - Produce a commissioning plan to help solidify the need for diagnostics.

G. Neil - Evaluate the effect of the M56 at the first chicane into the wiggler.

G. Neil/C. Bohn - Establish a Mission Statement.

D. Douglas - decide on the positions of the six diagnostic items in the return leg.

D. Douglas - We need tracking runs on the machine to find the second order effects.

All Cost Account Managers - Identify and get on order the long lead items. In particular, the vacuum.

C. Bohn - Establish a clean statement of the energy range of the machine.

C. Murray - Add the more complete view of the cryogenic lines to the layout and start the cross sections. M. Zarecky has a start of the cross sections.

D. Kashy - Resolve if the spare position U tubes interfere with the optical chicane magnets.

K. Jordan - Get C. Bohn, G. Biallas, C. Murray to agree on a method of mounting a mirror in the end dipoles to extract synchrotron light for diagnostics or require the change to a different style magnet.

C. Murray - Substitute the icon for the Injector Dump to the straight ahead dump position and as shielding to all the dump configurations.

Completed Action Items:

C. Murray - remove the cookie cutter beam tube transitions at the dump chicane after the cryomodule. Complete.

J. Parkinson - Find out how effective the electrostatic precipitator at the front end of the first linac was. Unable to be assessed, the precipitator was washed without analysis. As a future action item, we should assess a precipitator at the next shut down. Complete.

S. Benson/R. Boies - Layout the proposed Optical Cavity. Complete.

C. Murray - Put parallel faces on the optical chicane dipoles. Complete.

C. Murray - Add a 6 inch wide tube to the chamber intersections at the injection crotch, dump crotch and laser mirror ports. Complete.