Free Electron Laser Commissioning/Diagnostic Meeting
Tuesday, July 23, 1996
Recorder: R. Legg
Next Meeting
- Date: July 30, 1996
- Time: 3:00 - 4:00
- Place: Test Lab Conference Room
Attendees
P. Piot, D. Douglas, R. Ursic, C. Bohn, D. Kehne
R. Legg, S. Benson, G. Neil, P. Kloeppel, and G. Krafft
Corrections to Previous Minutes
- Leigh pointed out to me that the focusing terms in dipole magnets which are a
problem in the injection chicane dump, while of
higher order than the dipole term, are linear and do not constitute "higher
order modes" as reported in last weeks minutes.
- C. Bohn wanted it clarified that the burnthrough calculations from
last weeks meeting would still allow the use of 4-channel BPMs in the machine.
Items of Discussion
- Dave D. reported on the 10/42 MeV magnet which had been suggested to phase
the cryomodule that he had been playing phone tag with Leigh and the action
was postponed until next week. Dave also reported that G. Biallas had been
reluctant to consider building another type of dipole for this purpose.
Court and George were surprised at this and the action was left with them to
discuss with George Biallas the strengthened magnet.
Dave received concensus support on the point that it made sense to have a
permanent system in place to check the phase of the cromodule.
- P. Kloeppel presented more burnthrough calculations. He made an error in the specific
heat of the materials last week and the temperature rise is 50 K not 3000 K depending
on the incident angle of the beam for a 600 um,250 usec, 600 uA, 42 MeV beam. He
stated that 250 usec long macropulses should not be a problem for a tune up mode.
As a result, the tune up mode for the machine was defined as:
625 uA peak
9 MHZ repetition rate
135 pC/upulse
250 usec macropulse width
1 - 5 Hz (1 Hz thread)
Less than 1.5 uA average
B. Legg has the action item of getting this information to K. Mahoney and starting
the MPS design moving and reporting back next week.
- C. Bohn said that the cryounit pair had been chosen. The first cavity was a
9 MV/m, and the 2nd is 12 MV/m. George Neil asked which orientation were the
SRF people using for their numbering? Court didn't know and will find out.
ACTION ITEMS:
D. Kehne will simulate the effect the assymetric powering of the unit
will have on the beam and the sensitivity of the beam to the assymetry.
8/6/96.
- D. Douglas said that by the inclusion of one more of the 10 MeV chicane dipoles
the dump can be designed to very good momentum resolution for phasing and a good
place for an emittance measurement. This sounds like an excellent option and
Dave will pursue the design for inclusion in the machine design, but he needs to
know what diagnostics the dump will include.
ACTION ITEM:
G. Krafft will schedule a meeting to discuss dump diagnostics this week.
New Issues
- G. Krafft has been in contact with CERN. They will be "retiring" about 2.7 GV
of 352 MHz SRF cavities in the next 2-3 years. He thinks we need to stay in touch
with them to either form a joint project or to try and obtain some of the cavities
for a high power FEL.
- R. Legg discussed ARR with J. Boyce. They have a tentative plan.
ACTION ITEM:
Legg to report on ARR plan 8/23.
- C. Bohn said that the commissioning strategy is not being reported
in these minutes and needs to be put on the web as it becomes
available to fill in gaps left in the minutes.
ACTION ITEM:
Legg to post tentative commissioning strategy and
reorganize the commissioning web pages to show
commissioning plans, experimental test plans, and schedules
clearly by 8/6/96.
Action Items
- A-37 D. Kehne will simulate the effect the assymetric powering of the unit
will have on the beam and the sensitivity of the beam to the assymetry.
8/6/96.
- A-38 G. Krafft will schedule a meeting to discuss dump diagnostics this week.
- A-39 Legg to report on ARR plan 8/23.
- A-40 Legg to post tentative commissioning strategy by 8/6/96
Action Items (assigned)
A-01 Update Drawing Bohn weekly
A-02 Magnet Specifications Webbed Douglas
A-04 Unit gradient precision Bohn, Liu
A-05 Injector energy precision Douglas
A-06 10 MeV dump optics Douglas
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-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-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-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-32 10 MeV emittance Plan Bohn
A-33 FSD Plan Mahoney, Legg
A-34 Consistent Linac phasing plan Yunn
A-35 simultaneous transverse and longitudinal Kehne/Engwall 8/6/96
A-36 'bad' injection dipole/dump geometry. Douglas 7/30/96
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 Legg 5 min
* New issues 10 min
* Simultaneous longitudinal/transverse tests Kehne/Engwall 10 min
* BPM can design Jordan/Yunn 5 min
* 10 MeV Dump design Douglas 10 min
* Agenda for next meeting All 5 min