Next Meeting
Attendees
C. Bohn, D. Douglas, L. Merminga, G. Neil, R. Legg, S. Benson, D. Kehne, and G. Krafft
Items of Discussion
There were no changes to the minutes. There were several organizational issues that were discussed, in the interest of getting through the meetings more expeditiously. First, in the interest of forstalling non-convergent discussions, when an issue comes up for discussion that cannot be resolved amicably with a minimum of fuss, an off line meeting will be called for to determine a method for dealing with the problem. If it is determined that an agenda item is required, it will be added in the following meeting. The agenda will be adhered to as much as possible. Also, in order to better coordinate with the Thursday FEL mechanical meeting, an additional permanent agenda item, called new issues will be added. This item will cover the items that might be generated in the mechanical meeting, or any other items that might arise during the course of the week. In order to add items simply e-mail G. Krafft. During the course of the meeting the new items will be discussed in turn and either (1) resolved (including an assignment of an individual to close the issue with the issue's ``generator", (2) assigned an off-line investigation group consisting of relevant parties, or (3) added to the action item lists. In any case, the process to resolve the issue should be the main focus of the discussion in cases (2) or (3) above. To repeat, the intent is to reduce unproductive meeting time, and to replace it with presentations where people present and discuss work and work progress towards resolving outstanding issues. Enough Geoff on his high horse.
From last time. There was a magnet meeting involving Bohn, Douglas, Harwood, Biallas, and Krafft on Monday. The meeting confirmed that we don't have many choices here. We will continue the next six months with the QBs as our quad design. In parallel, Dave will complete his analysis, and necessary modifications will be made based on his results.
New Items
Wiggler instrumentation and planning. George gave an update on the start of a commissioning workshop plan. As many of us will be involved at some level the advice is to stay tuned; he and Benson will be the main contacts on this planning. No furthur action needed.
Dipole gang power scheme. It was clear that the mechanical people would like some action on this. Tentatively, Douglas will coordinate with Biallas on this one.
Requirements and reviews for diagnostics. It was proposed that the topic be rediscussed next week when Jordan is here in order to get the best input.
Flip viewer. Kehne stated that given the (as yet undesigned) IR camera is available, such a device is not necessary. Issue closed.
Shielded viewers. Wait for Jordan to discuss. Only the ones before to FEL have to be shielded.
Overpower dipole after cryomodule; microdumps. This item continued a discussion of last week; Benson strongly for the proposal. It was agreed generally that it was a good idea to have the device; accomplishing it seems to require doubling up the magnets. It was also mentioned that it might be a good idea to deep-six the wiggler bypass; there is going to be path length pain in going from bypass mode to non-bypass mode. Benson will make sure the changes get made.
Assess need for Faraday Cup. No firm resolution of issue. It was felt that monitoring to the few percent level was probably sufficient, and it was agreed that there was no provision for this in the current plans. A pending action item was added. We need a general plan for current monitoring.
Special OTR viewers in chicane. The dimension has to be large enough to handle anticipated energy spread. Five percent times 60 cm dispersion yields 3 cm spots. Having a 5-6 cm viewplate or larger visible at these locations should do it. Benson to coordinate with K. Jordan to get issue resolved. No furthur discussion required.
Powering of back-leg magnets will also be handled by D. Douglas as above.
Action Items (assigned)
Substantial progress was made by Benson on the question of whether more than 2 SEEs are needed in the wiggler region. To paraphrase his conclusion; only two BPMs with a precision the same as the SEEs will provide a pointing accuracy about ten times better than typical optical envelope angles (50 mum compared to 750 mum). Consequently, having more BPMs, which could only improve the orbit in the wiggler by at most a squareroot of N effect, will improve the precision beyond the point of diminishing returns. Basically, to the extent the BPMs don't drift, extra BPMs won't help much. The issue is marked complete, Benson said he will try to get his report up on the Web!
First Cut List of Commissioning Tasks
The following list was started for commissioning the Injector Test Stand by D. Kehne and G. Krafft. It is only a first cut and should be added to and modified through e-mail to G. Krafft. The list is a partial answer to the question: what does it mean for the Injector Test Stand to be done?
C-1 RF gradients verified C-2 Operational RF phases determined C-3 Drifts (of phases if like main machine) quantified C-4 Gun current verified/operational procedure complete C-5 Beam jitters determined C-6 Cryounit Focussing/Convergence determined C-7 High power CW beam is delivered for ``awhile'' C-8 Cathode lifetime studied C-9 Engwall/Kehne studies on gun transverse/longitudinal emittance complete C-10 PARMELA ``verified''
After the move to the FEL building the following tasks must be completed to prepare the beam for injection into the linac.
C-11 Transverse phase space at injection verified C-12 E-beam matched at injection point C-13 Longitudinal phase space verified C-14 Longitudinal tilt checked at injection C-15 Above determined at high power
Action Items (assigned)
A-01 Update Drawing Bohn 4/16/96 A-03 Stray fields in test stand Legg complete A-04 Unit gradient precision Bohn, Liu 4/16/96 A-05 Injector energy precision Douglas 4/09/96 A-06 10 MeV dump optics Douglas 5/14/96 A-07 Bypass optics Douglas 4/30/96 A-08 M56/RF phasing and beam load issues Neil, Douglas, Liu A-09 Dump Instrumentation Legg 5/23/96 A-10 Back leg diagnostic placement Douglas 5/30/96 A-11 Multifrequency CSR Measurements Krafft 4/30/96 A-12 How should the path length be checked? Krafft, Jordan 4/30/96 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 4/30/96 A-18 Trombones Douglas, Krafft 4/09/96 A-19 Experiment Plans, 10 MeV line, etc. Kehne 4/09/96 A-20 More than 2 SEEs in wiggler regions Benson complete
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-06 Web Documentation
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-17 Gang of power supply for backleg quads
(must include emittance meas. capability)
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-22 FSD plans
P-23 Transverse Effects in CSR
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
Agenda for Next Meeting
Item Person Responsible Time
---- ------------------ ----
* Review agenda/corrections to minutes Krafft 5 min.
* New drawing Bohn 5 min.
* New issues
Requirements and reviews for diagnostics Jordan
Shielded viewers as bolt-in upgrades of regular viewers
Overpower dipole after cryomodule; a microdump?
Assess need for faraday cup
* Task List Discussions All 30 min.
* Web documentation Krafft
* Agenda for next meeting All 5 min.