Free Electron Laser Commissioning/Diagnostic Meeting

Tuesday, April 17, 1997
Recorder: R. Legg

Next Meeting

Date: April 22, 1997
Time: 3:00 - 4:00
Place: Test Lab Conference Room

Attendees

Attendees
---------------

R. Legg, C. L. Bohn, Q. S. Shu, K. Jordan, J. Bennett, L. Merminga, G. Neil, G.A. Krafft, B. Yunn, D. Douglas Addenda/Errata to Previous Minutes
-------------------------------

  • none Items of Discussion
    ----------------------

  • B. Yunn presented his latest PARMELA runs simulating 0, 60, and 135 pC/bunch cases transported through a lattice optimized for the 135 pC case. The slides are available on the www at:

    www.cebaf.gov/~legg/041897_comm

  • The first .gif shows the numbers for the 60 and 135 pC cases. The second .gif shows how the betatron functions evolve for the 0 pC case in the 135 pC lattice. The horizontal units are element numbers and the end of the unit is at about 16, the start of the module at about 34 and the end of the module about 55. The plot goes to the front of the wiggler. The betatron functions for the low charge case are the worst raising concerns about where the ghost pulses are going to go.

  • The third .gif file shows the 60 pC case. It looks like good news in that the beam should be transportable in CW with this lattice. The fourth .gif file shows the 135 pC case. Note that the peak in beta Y occurs in the "X" region of the injector. This could be a problem depending on the height of the chamber.

  • The fifth .gif file shows a table of the sigmas, emittances and dp/p for the three charge per bunch settings at various spots along the lattice.

    The last .gif file shows a table of the alphas and betas at the three charge settings along the machine.

  • B. Yunn agreed to pass his numbers to D. Douglas to get DIMAD tracking around the rest of the machine to look for other problems.

  • We discussed the OTR size issue. The problem was that there was a requirement to run CW beam through the OTR foil while trying to lase. This set constraints on the size of the foil. G. Krafft set he would talk to S. Benson and E. Feldl and settle the issue if the CW vs. pulsed issue could be settled. He subsequent to the meeting talked to all parties and settled on a 0.75 by 1.5" OTR.

    New Issues
    ----------

  • D. Douglas says that the multipole field in the air core Haimson coils is higher than that in the fast corrector magnets. George Biallas has suggestted that we add some of the high mu material to the correctors to bring them within the 1% field flatness specification. Dave agreed to verify that adding the iron would indeed solve the problem.

    Action Items
    ------------

  • None 
       
Action Priority  Items (assigned)
----------------------------------

A-05   2  Injector energy precision                     Douglas
A-15   1  Commissioning Procedure                       Legg, Krafft    5/16/96
A-19   0  Web Documentation                                             weekly
A-20   1  10->42 MeV dump                               Douglas
A-24  1,2 Beam loss                                     Bohn
A-29   1  Software Planning for Longer Term             Bohn, et al.
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-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-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

Action Items (pending)
------------

P-02  1   Laser phase modulator						Jordan
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-14  1   How is the gun/laser operated?				Benson
P-15      Discussion on robustness of controls				Legg
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-29  2   FEL/linac interaction						Merminga
P-30  2   Tracking including realistic wiggler fields			Douglas
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.
    *	Optics issues					Douglas		 20 min
    *   Milestones for ER test plans			Legg		 20 min
    *	New issues					All		 10 min
    *	Agenda for next meeting		                All		 5 min.