Minutes of the IR FEL Beam Transport Meeting, July 11, 1996

Meetings are held in Room 84, Trailer City on Thursday at 1:30 P.M.

ATTENDEES: S. Benson, L. Dillon-Townes, R. Legg, G. Neil, C. Murray, M. Wiseman

Decisions/Comments:

Fred Dylla recommended to the M7 that we proceed with the 45 MeV design. We will start looking at the upgrade after the present design work is done and we have a DIMAD file for the 75 MeV design.

C. Murray presented Layout #7, dated 7/11/96. This incorporates the latest information from D. Douglas. He has also added figures for EP's on either side of the CM.

We discussed the locations and design of the beam scrappers. P. Kloeppel has provided EGS runs for 50 and 200 MeV. For 8.9 inches of copper the energy remaining is 2.3 MeV and 11.4 MeV for 50 MeV and 20 MeV respectively. It was felt that this was probably adequate for the scrappers. C. Bohn's original thoughts put the scrappers in the two inch straight sections just upstream and downstream of the optical chicane. Should the scrappers be located in the 4" and 8" oval pipe so that the spray downstream of the scrappers is aimed at less critical items? Action item for C. Bohn.

Action Items:

L. Dillon-Townes/C. Murray/B. Yunn - Maintain latest layout/ define the vacuum tube at all discontinuities, refine impedance analyses and write the Tech. Note. Definition of discontinuities half finished.

C. Bohn - Establish a clean statement of the energy range of the machine. Authorization for nominal upgrade 75 MeV dipoles (Actual design point 79 MeV) was given by M7. F. Dylla to present recommended plans for upgrade to the M7 on Monday.

D. Douglas - Check if the existing QJs can be used in the new injection line and publish the injection line. No action

G. Biallas - Get the BT contracts signed. Contracts needed to be changed to new DIMAD configuration. No action.

T. Siggins/K. Jordan - Review proposed Shielded Viewers for vacuum construction properties. T. Siggins reviewing the drawings. {Closed}

G. Biallas - Start definition of a girder for the wiggler, diagnostics and quad telescopes that maintains position of the elements within 50 µm (0.002 in.) during change-out of the wiggler. M. iseman to appoint an engineer. {Waiting on the wiggler design. Al Guerra will be the engineer}

L. Harwood - Determine if placing additional dipole(s) or temporarily substituting a stronger dipole at the first dipole of the dump chicane after the cryomodule is the best method of bending pulsed 42 MeV beam into the dump during cryomodule phasing. No action. Prototype Reverse bend Dipole could be supported with existing power supplies. Commissioning using this procedure appears to be viable. {This is still being studied at the commissioning meeting. May want to have this ability full time.}

G. Biallas/L. Harwood - Provide a good value for field enhancement factor for the style of magnets we are anticipating. Verify the K value of 0.45 that D. Douglas uses in his optics calculations. Bids for the prototype dipole are due today .

C. Bohn - Have B. Yunn establish the vacuum specification for the remainder of the vacuum system using the criteria of ion trapping. {Rough calcs show no problem. B. Yunn needs to talk to D. Kehne. G. Neil feels that the impedance studies take priority over this. The vacuum design will proceed with the current specs.}

G. Biallas - Examine the categories on the Web and propose alterations. No action.

C. Bohn - Have B. Yunn examine the impedance effects of a 4 inch wide pipe in the optical chicane area. Cross sections provided,; first glance appears that there is no problem. {S. Benson would like to see some detailed numbers on this. He has concerns about operating the FEL at high harmonics.}

E. Feldl - Construct and test a Prototype Sparse Lamination Quad. Damaged board in the Magnet Measurement Stand is repaired. Start of measurements is 3 weeks away.

M. Wiseman - Thermal analysis of the 45 MeV Dump for 30 kW & beam scraper analysis for 45, 79 and 200 MeV. P. Kloeppel has finished 50 MeV and 200 MeV EGS runs. Thermal design has started.

New Action Items :

R. Legg - Check D. Douglas' numbers on the new DIMAD. Started

New Action Items for the Vacuum Meeting:

L. Dillon-Townes - Assess the pumping and power supplies required near the dumps in order to maintain the vacuum at the beam line at the 10-8 level.

L. Dillon-Townes - Propose how we do differential pumping.

Summary of Minutes from July 10, 1996 Vacuum Meeting

Dillon-Townes/Murray: Provided layout and tabulation to B. Yunn of machine elements for impedance study. Dimensions of bellows, beam scraper, and electrostatic precipitator are being developed.

D. Douglas: Dillon-Townes requested that the exit angle of the Injector Dump Beamline Chamber be nailed down. In addition, DIMAD data for the elements in this line be supplied.

Wiseman: reports that at the 95% level of beam absorption the scrapers would need occupy 12" - 15" of beamline space. Refinement in process.

Wiseman/Parkinson: The electrostatic precipitators have been added before and after the cryomodule on revision 7 layout. The question as to whether the precipitators are located before or after the vacuum valves is still open.

B. Yunn: Quantitative values for the ion trapping and impedance requested for the 4" chicane study.

Dillon-Townes/Parkinson: Space limitations drives the proposal to install a large capacity pump at the large vacuum chambers instead of differential pumping. The size and vacuum chamber configuration will be determined.

Dillon-Townes/Murray/Parkinson: Define the breakout regions to start detail designs once vacuum specification is established.

Dillon-Townes/Murray: Investigate and define bellows design (shielded and unshielded).

Feldl: OTR's beyond the wiggler may not be shielded. Standard cross proposed to be used.

New Action Items from the Diagnostics/Commissioning Meeting:

None

Completed Action Items:

W. Merz - Determine from the actual response of power supplies with respect to jitter, short term drift and long term drift. Analysis written. Complete.

G. Neil - Find out if the mirror mounts can fit and function within proximity of the optical chicane dipoles. Yes, Complete.