Free Electron Laser Commissioning/Diagnostic Meeting
Tuesday, DEC 10, 1996
Recorder: R. Legg
Next Meeting
- Date: Dec 17, 1996
- Time: 3:00 - 4:00
- Place: Test Lab Conference Room
Attendees
G. Neil, M. Wiseman, D. Kehne, L. Merminga, B. Yunn, J. Bennett,
R. Legg, C. Bohn, S. Benson and D. Douglas
Addenda/Errata to Previous Minutes
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- Long term software tasks on the task list should be updated
to reflect the results of the software prioritization meeting.
- The shift of stable beam prior to installing the wiggler
reported in the previous meeting should be corrected to a
shift of stable CW operation.
- The 5 um out of 100 um initial cavity search reported in the
last minutes is actually 5 um out of +/- 100 um initial
alignment accuracy. A factor of two more difficult.
- The new lattice by Douglas has 501.5 rf wavelengths around
the ring to the reinjection point. See his webpage at the
Fodomat for your IR-FEL needs.
- D. Kehne says he may be able to shorten the 4 m drift after
the second expander quad by powering the QJ's used up to
15 or 20 amps. J. Karn says that the magnets can handle the
power, but Kevin is worried about the non-standard DC power
supplies.
Dave also said he thinks he can use a 4 x 2" BPM chamber on
the dump. This would make it common with the optical
chicane cans and reduce the number of wide designs to three.
Items of Discussion
-------------------
- L. Merminga discussed the droop and stability that could be
expected from pulsed 1.1 mA operation of the beam with the
8 kW klystrons. The good news is she says the rf and beam
will be stable. The bad news is that there will be a
delta E/E of 2.5e-3 and a phase slip of 0.06 degree on the
rf in the cavity which will be communicated to the electron
beam. This will effect measurements made with pulsed beam
prior to trying to lase that integrate over the pulse. The
momentum spread measurement which uses the OTR's is an
example. The emittance measurement at the wiggler should not
be effected however.
As an upshot we will need to change the technique used to do the
momentum spread measurement.
- Byung presented his results for simulations to date. He has
changed his transport deck to operate the unit off crest to
reduce the dp/p to 0.015%. He also says he can achieve almost
any combination of bunchlength and momentum spread at the
wiggler and without further restraints can't choose an operating
point. He says he cannot give me a solution which allows a
transition from 1.1 mA to 5 mA without changing rf phases.
S. Benson proposed:
Come up with design rules
Use the envelope equation to set baseline design
Use PARMELA simulations to fine tune the design
Byung did warn that he had seen some large discrepancies
in the results from runs where the only change was going
from 500 to 1000 particles. He said that one should
therefore take any results with a grain of salt.
- Byung also handed out his latest impedance results, the
bottom line is that there were a few design issues to work
with Mark Wiseman, but the design was well within the original
impedance budget.
New Issues
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Action Items
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Action Priority Items (assigned)
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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 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-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-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-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-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
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Item Person Responsible Time
---- ------------------ ----
* Review agenda/corrections to minutes Legg 5 min.
* 350 keV Experiment Kehne 40 min
* New Issues ALL 10 min
* Agenda for next meeting All 5 min.