Free Electron Laser Commissioning/Diagnostic Meeting
Tuesday, June 25, 1996
Recorder: G. Krafft
Next Meeting
- Date: July 2, 1996
- Time: 3:00 - 4:00
- Place: Test Lab Conference Room
Attendees
D. Douglas, J. Denard, C. Bohn, P. Piot, K. Mahoney, R. Li,
R. Legg, S. Benson, G. Neil, K. Jordan, G. Biallas, and G. Krafft
Items of Discussion
- There is one change to the minutes last week. D. Kehne reminded me that
he was back from Brookhaven and attended last week's meeting. Sorry for
the oversite.
- Two organizational issues were discussed. First, in an effort to get some
more rigorous planning done for the FSD system in particular, but also
more generally for the PSS and MPS, K. Mahoney has agreed to lead and
coordinate efforts on these issues for the FEL. Such help is both timely,
and needed. Thanks, Kelly.
- Likewise, B. Legg has agreed/been persuaded to coordinate and oversee the commis-
sioning effort for both the ITS and FEL. As such he will be responsible for developing
commissioning plans, start-up procedures, and ultimately, a user manual when
we get to that stage. In order to more efficiently procede, it is natural that he
lead this particular meeting; starting next week. I (G. Krafft) will start to
concentrate more on diagnostic issues, both in coordination and research roles.
I hope to get some of the longstanding active issues assigned to me on these topics
out the door.
- During the standard drawing discussion it was noted that a tentative solution
to the interference problem between the chicane magnet coil and optical cavity
mirror had been found. The solution involves a rotation and reflection of
the can. This solution also moves the stepper motor out of the magnetic field of
the coil, reducing the need to be concerned about its proper operation.
- Douglas reported that he was no longer sure what had been promised as far as
energy goes. The final number has some bearing on the injection energy ratios
and should be documented. After a bit of discussion it was concluded that the
right number is 42 MeV kinetic energy, about 42.5 MeV total energy with the
rest mass included.
New Issues
Possible Upgrade: Court related that it is seeming more likely that there
might be so-called follow-on money to support an energy upgrade in the
next budget cycle. This has an immediate effect on Douglas, Biallas, and
Bohn in the vien of planning an upgrade to the 80 MeV level (essentially
an additional cryomodule and additional magnet capability). A detailed policy
proposal will be developed over the coming weeks so stay tuned.
Until it's stated otherwise, we will continue to work on the 42 MeV machine.
The information did cause some additional discussion about the purpose of
the FEL for the longer term, and it was pointed out that the two critical
issues, injector performance and beam recirculation performance, are just
as well studied at 42 MeV, and perhaps we should concentrate on them. Jordan
also related that getting an additional HPA is liable to be an issue. One
agreement that was reached is that the two designs should be called the
42 MeV design, and the 75 MeV design in future discussions.
Synchrotron Light Monitor plans: again no meeting occurred.
A meeting with Denard, Piot, Jordan, Benson, Krafft, and Bohn should be scheduled.
Action Items
- A-03 No documentation confirmation as of 4/9/96.
- A-19 A preliminary version of the documentation tree (hierarchy) is finally posted!
The upper level laser requirements are also posted! Take a look and make comments.
- A-26 Neil reported further progress on the IR camera. He presented a list of potential
applications and preliminary estimates of signal to noise issues. The list seemed
complete (no-one objected that their application was missed) and Jean Claude and
Phillipe, who have been looking at this issue independently, agreed with George's
general conclusion that from a signal to noise point of view, shorter wavelengths
are preferred. His guess was that we would concentrate in the 1-5 mum range, and
that we would have several cameras for different applications. He agreed to
schedule a coordination meeting on Thursday or Friday, so we can solidify the
plans.
- A-27 Douglas presented more findings on Autosteering. He summarized the current
dignostic plan and said that it could be steered (automatically if the OTRs
could be made automatic), the restore could be verified, the emittance
measured, and the optics verified with the complement of 6 BPMs and 6 OTRs.
However, there will be some blind spots to a BPM-based Autosteer. Adding
BPM cans to every quad, and redistributing electronics channels to high
beta BPMs could provide BPM-based autosteer capability. Since all back-leg
quads could be integrated into a modular quad-BPM girder, and potential savings
accrue, it was felt that the additional expense for having the cans was
"in the noise" and there was general agreement that we should procede with 12
BPM cans on the back-leg. This discussion, aside from documentation, also
closes the back-leg diagnostic placement active issue.
- A-28 R. Li presented results on her initial attempts on the transverse problem in
CSR. The approach is a generalization of the calculation she has recently
published, only including potential transverse offsets. Ultimately, a complicated
integral over the (evolving) bunch distribution will have to be done. She was
a bit uncertain as to when she could have some testable predictions, but was
encouraged to think in those terms so that diagnostics planning could include
a significant test.
Action Items (assigned)
A-01 Update Drawing Bohn weekly
A-02 Magnet Specifications Webbed Douglas
A-03 Stray fields in test stand Legg complete
A-04 Unit gradient precision Bohn, Liu
A-05 Injector energy precision Douglas
A-06 10 MeV dump optics Douglas
A-07 Bypass optics Douglas
A-08 M56/RF phasing and beam load issues Yunn, Neil, Douglas, Liu
A-09 Dump Instrumentation Legg 6/04/96
A-10 Back leg diagnostic placement Douglas
A-11 Multifrequency CSR Measurements Krafft 6/04/96
A-12 How should the path length be checked? Krafft, Jordan 6/11/96
A-13 Impedance Layout for Wiggler Yunn, Neil complete
A-14 Reduce M56 to under 30 cm Douglas complete
A-15 Commissioning Procedure Legg, Krafft 5/16/96
A-16 Average Current Measurement/Assess Far. Cup Legg
A-17 4-Channel BPM on the IRFEL Bohn, Denard
A-18 Trombones Douglas, Krafft
A-19 Web Documentation Krafft weekly
A-20 10->42 MeV dump Biallas
A-21 Diagnostics reviews Jordan 6/11/96
A-22 Beam dump and scaper design Wiseman 6/18/96
A-23 Ganged powering schemes Douglas
A-24 Beam loss Bohn
A-25 Synchrotron Light Monitors Krafft
A-26 IR Camera Plan Neil
A-27 Autosteer Plan Bohn
A-28 Transverse Effects in CSR Li
A-29 Software Planning for Longer Term Bohn
A-30 Burnthrough/Conflat Expansion Denard, Kloppel
A-31 S/N for SR to blackbody Piot
A-32 10 MeV emittance Plan Bohn
A-33 FSD Plan Mahoney, Legg
A-34 Consistent Linac phasing plan Yunn
Action Items (pending)
P-01 Determine Beam Pulse structure for setup
P-02 Laser phase modulator
P-03 Slit emittance measurement
P-04 Is an energy compression scheme needed?
P-05 Devise fine-tuning procedure for buncher gradient
P-07 Diagnostics "Freeze"
P-08 How do we change energy? What is the energy range?
P-09 Do we need bunching after the module
P-10 Will the SLM monitor work to center the large beam
P-11 Calculate from Hall C data how much scatter the BPMs can take
P-12 FEL/OTR interaction question
P-13 Do we have sufficient diagnostics for emittance degradation measurements
P-14 How is the gun/laser operated?
P-15 Discussion on robustness of controls??????
P-16 Injector diagnostics in the main machine
P-18 Technote by Yunn summarizing machine impedance
P-19 Consistent linac/bunching phase sets
P-20 Lock plans (who in particular)
P-21 Save/restore plans
P-24 FEL Commissioning review
P-25 RF control sensitivities/Microphonics Diff for FEL/Pathlength effect
P-26 What if studies
P-27 Plan to measure beam loss
P-28 Scrapers: Where and How?
P-29 FEL/linac interaction
P-30 Tracking including realistic wiggler fields
P-31 What drives the vacuum spec.
P-32 Are two sextupole families enough to tune M56
P-33 Is path length feedback needed?
P-35 Coordinated ITS beam running/SRF commissioning plan
P-36 Beam power robust BPMs
P-37 42 MeV dump design and interlocking
Agenda for Next Meeting
Item Person Responsible Time
---- ------------------ ----
* Review agenda/corrections to minutes Krafft 5 min.
* New drawing Bohn 5 min.
* Web documentation Krafft 10 min.
* New issues
* IR Camera Plan Neil s15 min.
* Active item discussion All 10 min.
* Agenda for next meeting All 5 min.