Next Meeting
Agenda for Next Meeting
Item Person Responsible Time ---- ------------------ -------- Status of Open Action Items All 5 min Commissioning Schedule Bohn 10 min Status of Diagnostic Procedures Piot 20 min Happek Bunch-Length Monitors Krafft 15 min New Issues All 5 min
This Week's Attendees
J. Bennett, S.Benson, G. Biallas, C. Bohn, J. Boyce, D. Douglas, F. Dylla, J. Fugitt, A. Grippo, K. Jordan, R. Li, L. Merminga, G. Neil, D. Oepts, P. Piot, M. Shinn, M. Spata, Q.-S. Shu, S. Suhring, R. Walker, B. Yunn
Closed Action Items
Items of Discussion
This week was devoted to continued preparation for resumption of commissioning. Bake of the gun was completed. High-voltage processing to 420 kV was also completed, and we made a cathode today (Friday, 29 May 98). Plans are to turn on electron beam Monday morning, 1 Jun 98, consistent with the schedule we had devised two weeks ago.
The FEL Accelerator Readiness Review was held Wednesday, 27 May 98. Its essential outcome was an affirmation of the process we have in place to verify the readiness of the machine to support user experiments. One of the findings of the Review Committee was that an interim operating and safety envelope should be issued before resumption of accelerator operations. J. Boyce presented the draft envelopes at today^Òs meeting. G. Neil and K. Jordan pointed out that given the instrumentation for the FEL, the quantity most amenable to auditing is not electron-beam current, but rather electron-beam power at the dumps, for which calibrated radiation monitors could be used. Power at the injector and energy-recovery dumps is hardware limited, and so it was thought that only the straight-ahead dump needs monitoring. After the meeting, R. May was consulted and concurred that a radiation monitor could be configured and calibrated for this purpose. As a result of other post-meeting discussions, J. Fugitt was asked to assess hardware limitations and document them in the form of a memo for record, after which we will determine whether we need to instrument other dumps. Consequently, we were able to generate the interim envelopes, and our DOE site office approved them today.
Considerable progress was made in writing procedures to support the Phase Space Setup Metaprocedure. L. Merminga presented her proposed procedure for cresting and gradient calibration of the cryounit using dipoles and BPMs. There was considerable discussion of technical details that subsequently continued off-line. Suffice it to say that we now have three methods for cryounit setup, and after turn-on we are planning to implement all three in an effort to reconcile them and get them to agree as we refine the Golden (Save/Restore) File after resumption of commissioning. Other procedures drafted this week concern resteering after rephasing the cryounit and cryomodule, and rematching to the wiggler and dump. We also updated the procedure for difference-orbit measurements, and we completed a set of numerical simulations to ascertain better the expected beam quality at the locations of key diagnostics. So, to be specific, the following tasks supporting the Metaprocedure (as extracted from last week^Òs minutes) are complete, at least in draft, with remaining tasks listed at the end of these minutes:
IV. Finalize "Cryounit Cresting" Procedure Merminga
VI. Establish Tolerances on Phase/Steering Drifts
A. Drive Laser Yunn/Walker
B. Buncher Yunn
C. Tolerances on RF Phase Drifts
1. Cryounit Yunn
2. Cryomodule Douglas
D. Tolerances on Steering
1. Injector Yunn
2. Linac Douglas
VII. Develop "Resteer After Rephase" Procedure
1. Injector Yunn
2. Linac Douglas
VIII. Establish Expected Beam Quality Yunn
A. Multislit #1, #2
B. Happek #1, #2
C. M_55 #1, #2
D. Bunch Length at Cryomodule Center
E. Bunch Length at Exit of First Optical Chicane
(with Li)
XI. Revise "CW Setup" Procedure (to 2G02) Douglas
A. Minimize Bunch Length with Happek #2
B. Establish Clean Beam Transport to Dump
XII. Develop "Rematch to Wiggler, Dump" Procedures Douglas
XIII. Update "Difference Orbit Measurement" Procedure Douglas
Dr. Uwe Happek of the University of Georgia spent the early part of the
week with us. He delivered the hardware for the interferometric
bunch-length monitors and assisted with their fit-up. By the end of the
week the two devices were installed and aligned.
As mentioned above, commissioning is slated to resume 1 Jun 98. The general pattern of daily commissioning activities will nominally be: day shift working through the Metaprocedure, swing shift exercising the machine, and owl shift measuring beam quality. At first, though, we will need to concentrate heavily on diagnostics (as several people emphasized at todays meeting) getting the essential tools to work, developing user-friendly procedures, and training people so the tools can be used routinely to progress through the Metaprocedure. Consequently, there is a good chance we will in effect be doing two shifts of diagnostics each day, Owls and Days, which will necessarily involve Piot (on owls) and Krafft (on days). We will work the details depending on how things go. Formal staffing for the next two weeks, modulo some localized excursions already known to those affected, is:
1-5 Jun 98: Owls -- Walker, Piot (standby), 1 CEBAF operator
Days -- Douglas, Benson (standby), 1 CEBAF operator
Swings -- Siggins, Oepts (standby), 1 CEBAF operator
8-12 Jun 98: Owls -- Hill, Piot (standby), 1 CEBAF operator
Days -- Bohn, Neil (standby), 1 CEBAF operator
Swings -- Oepts, Shinn (standby), 1 CEBAF operator
New Issues
None.
New Action Items
Old Action Items
Test Plans in Work
Procedures in Work
Emittance Growth from CSR
Procedures Needed for Recirculation
Subsidiary Tasks for Phase Space Metaprocedure
Task Principal
---- ---------
I. Stabilize Drifts in Drive-Laser RF Phase Walker/Fugitt
II. Calibrate RF Gradients
A. Buncher Yunn
B. Cryounit Cavities Merminga/Krafft/Yunn
C. Cryomodule Cavities Merminga/Krafft/Yunn
III. Reconcile Methods for Setting RF Phase Merminga/Krafft/Yunn
A. Buncher Cavities
1. Energy fixed point
2. Minimum bunch length/time of flight
3. Transient phasing
B. Cryounit Cavities
1. Transient phasing
2. Cresting
3. Time of flight
V. Finalize "Injector Setup" Procedure Yunn/Biallas
F. Emittance at Wiggler, 2G02 (with Li)
G. Momentum Spread at Wiggler, 2G02 (with Li)
IX. Complete Diagnostics Procedures and Training Krafft/Piot
A. M_55 #1, #2
B. Happek #1, #2
C. BPMs
1. button calibration factors
2. rotated MEDM spike charts
3. difference orbit data acquisition script
D. Multislit #1, #2
E. Quad/Viewer (at Wiggler, after Wiggler)
F. Multimonitor (at Wiggler)
G. SLM/CSR
H. Zero Phasing
I. Momentum Spread (Injector, Linac Pre-Wiggler, Linac Post-Wiggler)
J. Energy
X. Develop "Injector Rematch" Procedure Biallas/(Unk. Physicist)
XIV. Update (as appropriate) "First Light" Procedure Benson