Free Electron Laser Commissioning Meeting
Friday, 10 Apr 98
Recorder: C. Bohn
Next Meeting
- Date: 17 Apr 98
- Time: "0845"-0945
- Place: FEL Facility Break Room
Agenda for Next Meeting
Item Person Responsible Time
---- ------------------ --------
Status of Open Action Items All 5 min
Scheduling and Commissioning Program Bohn/All 50 min
New Issues All 5 min
This Week's Attendees
J. Bennett, S. Benson, J. Bisognano, C. Bohn, J. Boyce, D.
Douglas, M. Drury, F. Dylla, J. Fugitt, A. Grippo, L. Harwood,
R. Lauze, R. Li, L. Merminga, G. Neil, D. Oepts, M. Shinn, R. Walker
Closed Action Items
- Yunn/Jordan: Prepare, label, and post to the "FEL operator
page" viewer images of PARMELA beam for the optimized 60 pC setup.
Status: There are hard copies in both the FEL and MCC Control Rooms, and these
have sufficed.So, this action is a "nice to have" but will no longer be
tracked.
- Yunn/Jordan: Prepare, label, and post to the "FEL operator
page" viewer images of zero-current PARMELA beam given the optimized 60 pC
setup.
Status: There are hard copies in both the FEL and MCC Control
Rooms, and D. Douglas's spreadsheet plots linac viewer images. These have
sufficed so far. So, this action is a "nice to have" but will no longer be
tracked.
- Neil/Siggins: Develop complete and concise machine shut-down
procedure for "storage" in Power Permit.
Status: Done and successfully used last weekend.
- Bohn: Deliver print of FEL layout to MCC Control Room.
Status: Done and in constant use.
Items of Discussion
This week's activities involved running high-average-current beam to the
straight-ahead dump and doing parametric studies of the
transverse emittance at the exit of the cryounit using one of the multislit
diagnostics. As of this writing (1150, 10 April 1998), we are
running 38 MeV beam at about 1 mA stably. With 60 pC bunch charge, the
nominal normalized transverse emittance at the exit of the cryounit was
measured to be about 6 mm-mrad in both the horizontal and vertical
directions. By comparison, PARMELA simulations predict 3.5 mm-mrad. Basically
we are off to a good start, but as noted below, we still need to decide how
to optimize the injector setup and what constitutes an adequate
setup. The answer lies ultimately in the beam quality at the entrance to
the cryomodule, and it awaits availability of both the multislit
diagnostic and bunch-length monitor at that point. The week's activities also
permitted us to verify operability of all of the beam position monitors
and the current-monitor cavity on the straight-ahead machine.
There is concern about alignment of injector components.
This week we moved the second solenoid down about 0.5 cm which enabled us to
center beam through the buncher cavity, both solenoids, and the cryounit.
Before moving the solenoid, we could not center through it but could
center through the other components (or so it appeared). C. Bohn will
set up an off-line meeting to identify key measurements that will lead to
resolution. All agreed that we need to harden the injector setup and then
"not touch it".
There was some discussion about next week's shift plans.
As it stands now, we will run sustained high cw current (hopefully 1.1 mA) to
the straight-ahead dump for three reasons: to monitor cathode
lifetime systematically, to watch for infant mortality, and to ensure our
high-power rf systems stay stable, especially the "8 kW" cryomodule
klystrons. We also have extensive time dedicated to diagnostics checkout
next week.
Regarding staffing for shifts, we will have two FEL'ers
and one CEBAF operator on every shift next week (from 0800 Monday through 2400
Friday, with Thursday day shift allocated to installation). Beginning
the following week, on 20 April, we will have only one FEL'er (with
another FEL'er on standby in case of emergency) and one CEBAF operator
assigned to each shift. Assignments for the next two weeks are:
13-17 April 1998:
- Owl -- Bohn, Hill, CEBAF operator
- Day -- Siggins, Merminga, CEBAF operator
- Swing -- Krafft, Shinn, CEBAF operator
20-24 April 1998:
- Owl -- Jordan, CEBAF operator, Piot on standby
- Day -- Yunn, CEBAF operator, Li on standby
- Swing -- Neil, CEBAF operator, Oepts on standby
C. Bohn led a discussion to delineate prerequisites to
inserting the wiggler and trying to get first light. Their "due date" is 1
May 98, which is the day the wiggler will be installed per the present
schedule. Prospects are reasonably good that we will be able to meet that
schedule! The prerequisites are as follows (they all have the same
priority!):
1. Support of CEBAF operators. Start using them NOW!
2. Stable 1.1 mA, 38 MeV beam.
3. Good (>10 hr) cathode lifetime.
4. Working diagnostics.
- Happek bunch-length monitor.
- Multislit transverse-emittance monitors (#1 is working, #2 is not).
- Quad/Viewer transverse emittance diagnostic at wiggler.
5. Adequate injector setup.
6. Working Analog Monitoring System.
7. Detailed procedures and test plans well communicated to MCC
staff (of which we have a good start courtesy of S. Benson).
8. Working optical transport, including Laser Safety System for
the Optical Control Room.
9. Great teamwork with some individual sacrifice ("individual"
was not named at this meeting).
R. Lauze and J. Fugitt highlighted some needs that have
arisen as a consequence of commissioning from the MCC (which started 6 April
as planned!). A list follows:
- Everyone needs to read and be familiar with the Accelerator
Operations Directives.
- Lauze asked that he be handed procedures and test plans that
are to be imminently executed so he can be sure they are understandable to
CEBAF operators and are distributed to them somewhat in advance.
- A weekend shift plan is needed so MCC staff will know what to
expect and/or monitor as the FEL is held over weekends in Power Permit.
- A simple machine turn-on procedure following storage in Power
Permit is needed.
- An FEL alarms handler is needed.
Other needs discussed off-line include an FEL Bugger Log that
will be kept in the MCC Control Room, which Bohn has already placed there,
and an FEL Operator Limits Log. Bohn envisions devising the latter once we
have a solution for 1.1 mA cw, 38 MeV beam into the straight-ahead
dump. His thinking is to use that setup as a starting point for
configuration control following discussions of the matter at previous FEL
Commissioning Meetings.
New Issues
L. Merminga raised the question whether the procedure for
ramping up the current needs revision. Based on how the tuners work, she is
leaning toward first setting the cryomodule cavities on crest, then
ramping the current, then taking the cavities off crest per Yunn's PARMELA
parameters. Eventually the magnetostrictive tuners will be working well
enough to make this a moot issue, but for now it is relevant. She will work to
answer this question early next week.
New Action Items
- Neil: Develop complete and concise machine turn-on procedure
following "storage" in Power Permit. (due by COB 10 Apr 98)
- Fugitt: Develop weekend shift plan, coordinate it with R.
Lauze, and hand it to Program Deputy. (due by COP 10 Apr 98 -- will be
needed every Friday)
- Bohn: Set up meeting to discuss injector alignment and
setup. (due 10 Apr 98 -- Bohn already set the meeting up
for 1330 10 Apr)
- Walker: Work with Operations Department to develop an FEL
Alarms Handler software page for use in monitoring the FEL
from the MCC Control Room. (due 17 Apr 98)
- All FEL'ers: Read Accelerator Operations Directives, a copy
of which can be obtained/borrowed from R. Lauze. (due 17 Apr 98)
- Merminga: Determine whether a change in procedure is needed
for ramping up the current, and if so, revise the existing procedure.
(due 15 Apr 98)
Old Action Items
- Hofler/Bickley: Recheck software link between FLOG and FEL
shift summaries. Status: Still undone, and Bohn needs to follow up.
(due 17 Apr 98)
- Mahoney: Prepare procedure "MPS/BLM Checkout for First
Light".
Status: Mahoney has been Program Deputy and so the action has been on
hold. J. Coleman personally assisted with the BLM checkout that has
permitted us to run cw beam, but we still need the written procedure for
reference later. (due 24 Apr 98)
Procedures in Work
Emittance Growth from CSR
- Tomographic Phase-Space Map Piot, 15 May 98
- Back Leg Thread Douglas, 6 Mar 98
Thread Beam around Machine, Top-Level Douglas, finalize 6 Mar 98
RF Stability during Energy Recovery Merminga, 6 Mar 98
MPS/BLM Checkout for First Light Mahoney, 8 Apr 98