Next Meeting

Date: Oct 22, 1996

Time: 3:00 - 4:00

Place: Test Lab Conference Room

Attendees

G. Neil, G. Krafft,R. Walker,JC Denard, K. Jordan, R. Ursik R. Legg, L. Merminga, C. Bohn, S. Benson

Addenda/Errata to Previous Minutes

• The alignment spec for the IR-FEL is not twice the value arrived at by D. Douglas' DIMAD runs. The two values agree but are only half as stringent as for the CEBA machine.
• Jean Claude Denard sent this on using an OTR at the 90 degree point of the bend and trying to propogating the beam down the backleg, "The beam gets 41 collisions in average through a 1.5 um Al foil (hope it is sturdy enough to install on the large screens). On BIW96 Philippe paper, a 0.5 % beam loss accurs for a 1/2 beam angle limitation of 1.9 mrad. For a 625uA CW beam, that would represent about 3uA CW loss. If we want to limit our losses 1.5 uA during the OTR use, my guess is that a 2.5mrad half aperture would be sufficient." This is roughly a 27x emittance growth and should propogate normally down the back leg for autosteer. Still doesn't settle the 90 degree BPM issue, though.
• R Legg needs to pass the required operating modes to R. Evans, STILL.

Items of Discussion

• Roc presented an update on how BPM's are calibrated. With the large chambers in the IR-FEL machine the coupling is too weak to allow calibration, but should allow Supercal to be used as a maintenance tool. This is much as the BPM's in the S. linac of CEBA are configured. The issue is do we want to cross calibrate the BPM's to the quad centers wherever possible? The concensus was yes, but we don't want to quad center 23 BPM's every day. Roc assured the group that these BPM's would be stable and he will calculate the result of the errors that will appear without the Supercal feature.
  

  We also may want to adapt the quad centering algorithm from CEBA to the FEL to speed initial BPM calibration.

  • Lia investigated the disconnect between B. Yunn's cryomodule phasing based on an optimal m5,6 and D. Douglas' real m5,6. After verifying that wakefield's are not a major perturbation, she ran D. Neuffer's code for a bunch with the "real" m5,6. She calculated a value 50% longer than spec for the bunchlength without space charge effects. Two questions came up, what is the bunch distribution assumed by D. Neuffer's code as it leaves the injector?, and how does space charge effect the bunchlength? The second question is of concern because Hongxiu has simulated the entire line to the wiggler with the 135 pC bunch and saw a short bunchlength. If the bunchlength requires a high space charge to be short with the present phasing scheme, will we have problems trying to get first light?

  • The steps to solve these questions:
    a. Check D. Neuffer's 1979 PAC paper and see if space charge can effect the bunchlength.
    b. Have Hongxiu rerun the entire line to the wiggler for the 135 and 33 pC cases and look at the bunchlength. If it is too long, adjust the injector accordingly.
    

  New Issues

  ---

  • Injector dump layout is still unclear to K. Jordan. Geoff will update the drawing according to D. Douglas' procedure and new slit layout.
  • Trim magnet placements - do the drawings match the DIMAD decks.
  • Insertable dumps There will be a meeting coordinated through Geoff.
  • High Level Software Applications coordinator. The original suggestion from Andrew was J Karn and he is unavailable now. R. Legg should worry about it but does not have time. Court is left to decide who takes this responsibility.

  Action Items

  ---

  • Geoff will update the injector dump drawing.
  • Geoff will coordinate a meeting on the insertable dumps.
  • Court will decide who should be addressing the high level application software issues.
    

    Action Priority Items (assigned)

    ---

    
    A-04   1  Unit gradient precision                       Bohn, Liu
    A-05   2  Injector energy precision                     Douglas
    A-06   1  10 MeV dump optics                            Douglas
    A-09   1  Dump Instrumentation                          Legg            6/04/96
    A-10   2  Back leg diagnostic placement                 Douglas
    A-15   1  Commissioning Procedure                       Legg, Krafft    5/16/96
    A-19   0  Web Documentation                             Jordan          weekly
    A-20   1  10->42 MeV dump                               Douglas
    A-24  1,2 Beam loss                                     Bohn
    A-29   1  Software Planning for Longer Term             Jordan (?)
    A-30   1  Burnthrough/Conflat Expansion                 Denard, Kloppel
    A-34   2  Consistent Linac phasing plan                 Yunn
    A-35   1  simultaneous transverse and longitudinal      Kehne/Engwall   8/6/96
    A-39   1  report on ARR plan                            Legg            8/23.
    A-41   2  Modeling of lower than 10 MeV injector        kehne, Liu      10/1/96
    A-42   2  2nd gun for long term tests                   Bohn            10/1/96
    A-44  1,2 Start Rui on emittance code                   Bohn            8/13/96
    A-45   1  decide on dump diagnostics                    Legg/Krafft     9/4
    A-46   1  specify the field quality in the
              dipole shut off to run straight ahead         Douglas         9/11
    A-47   1  OTR beam interaction number by                Denard          9/11
    A-54   1  FEL Turn-On Proc                              S. Benson       11/1/96
    A-55   1  Laser Diagnostic Proc                         Benson          11/1/96
    A-56   1  Proposal to vary laser intensity              Benson          10/22/96
    A-57   1  What is equivalent macropulse to CEBA viewers Legg            10/15/96
    
    Action Items (pending)
    
    
    P-02  1   Laser phase modulator                                         Jordan
    P-04  2   Is an energy compression scheme needed?                       Douglas
    P-05  1   Devise fine-tuning procedure for buncher gradient             Krafft/Kehne
    P-08 1,2  How do we change energy? What is the energy range?            Benson
    P-09  2   Do we need bunching after the module                          Douglas
    P-14  1   How is the gun/laser operated?                                Benson
    P-15      Discussion on robustness of controls                          Legg
    P-18  1,2 Technote by Yunn summarizing machine impedance                Yunn
    P-19  2   Consistent linac/bunching phase sets                          Yunn
    P-20  1   Lock plans (who in particular)                                Johannes?
    P-21  1   Save/restore plans                                            Benesch
    P-25 1,2  RF control sensitivities/                                     Merminga
                Microphonics Diff for FEL/
                Pathlength effect
    P-28 1,2  Scrapers: Where and How?                                      Bohn, Li
    P-29  2   FEL/linac interaction                                         Merminga
    P-30  2   Tracking including realistic wiggler fields                   Douglas
    P-32  2   Are two sextupole families enough to tune M56                 Douglas
    P-35  1   Coordinated ITS beam running/SRF commissioning plan           Legg/Bohn/Harwood
    P-37  1   42 MeV dump design and interlocking                           Wiseman
    
    Agenda for Next Meeting
    
    
                    Item                              Person Responsible     Time
                    ----                              ------------------     ----
        *   Review agenda/corrections to minutes            Legg             5 min.
        *   Updates to task list                            All              10 min.
        *   Proposal to vary laser intensity                Benson           10 min
        *   Setup outline for injector line                 Douglas          20 min
        *   New Issues                                      ALL              10 min
        *   Agenda for next meeting                         All              5 min.