Minutes of IR FEL Mechanical Systems Meeting, March 28, 1996

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

ATTENDEES: S. Benson, C. Bohn, D. Douglas, L. Harwood, K. Jordan, D. Kashy, D. Kehne, C. Murray, G. Neil, J. Preble, M. Wiseman, B. Yunn

Decisions/Comments:

IRFEL Baseline: The baseline IRFEL conceptual design is >"linac-wiggler-bend-bend". All further work is to focus on refining this design unless otherwise notified.

Mission Statement: Presently the main purpose of these Mechanical Systems meetings is to do technical integration of the IRFEL system. The meetings will focus on system-level issues and updates, and provide the opportunity to work together as a diverse group in updating the overall system drawing. The meetings will not deal with programmatics. Specialized working sessions are to be conducted elsewhere.

We resolved, insofar as possible, to hold all formal, technical meetings concerning the IRFEL in the Test Lab Conference Room. For example, the weekly IRFEL Diagnostics/Commissioning meetings will normally be held on Tuesdays at 3 pm at this location.

The following open action items are hereby relegated to the weekly IRFEL Diagnostics/Commissioning meetings:

- 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.

- G. Krafft - 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.

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

- Resolve how to do SLM with a big transverse beam size.

In the near term (next week or two) we shall strive as a group to resolve where we're comfortable with the IRFEL system design so we can freeze those aspects of the system and start the related purchases.

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.

C. Bohn - Obtain bunch lengths from photocathode to wiggler from H. Liu.

G. Neil - Get wiggler beamline drawing to B. Yunn.

C. Murray/J. Parkinson - Get nominal flange drawing to B. Yunn.

J. Bisognano/B. Yunn - Refine impedance analyses based on updated

IRFEL system design and bunch-length data.

D. Douglas/L. Harwood/S. Benson - Spec octupole content of wiggler.

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 hardware. Vendors are swamped!

C. Bohn - Establish a clean statement of the energy range of the machine. Status: Need help from Biallas/Harwood to plot cost vs. maximum energy for the magnetic optics. Division Leadership Group wants to see this data.

C. Murray/D. Kashy - 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. Resolve if the spare position U tubes interfere with the optical chicane magnets. Put cartoon in for transfer lines of 1/4-unit.

C. Murray - Put parts count on system drawing, e.g., #quads, #OTRs, #BPMs, etc.

C. Murray - Prepare illustration showing widened pipe (from 6" to 8") at "neck dipoles" in the 180-degree bending systems in preparation for feasibility/cost assessment.

G. Biallas/C. Murray/D. Kashy - Calculate required pipe-wall thickness in the vacuum chambers of the 180-degree bending systems.

J. Preble/D. Kashy - Spec cavity Q0.

Completed Action Items:

H. Liu/D. Douglas - Resolve effective length vs. actual length ratios in the injector dipoles. Per L. Harwood's advice, the dipoles have been lengthened to provide a ratio of effective length to gap slightly exceeding 4, and the injection line was proportionately lengthened. Normalized transverse emittance at the injection point is now 6.1 mm-mrad according to simulation. Harwood will need to design a variation of an H-magnet for this application, a feasible but challenging task. This is the now the baseline for the injection line, though Liu agreed in an off-line meeting to consider possible applications of indexed magnets as a backup.

G. Neil/C. Bohn - Establish a Mission Statement. Complete -- see under Decisions/Comments.

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. Complete --a Brewster-like mirror will be incorporated to direct the light into a 1-cm-diameter viewing port colocated with the magnet centroid. L. Harwood confirmed feasibility. It also might be possible to divide the 180-degree dipoles into two 90-degree bending magnets and insert SL diagnostics between them. This idea was relegated to back-up status.

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