Next Meeting
Agenda for Next Meeting
Item Person Responsible Time ---- ------------------ -------- Status of Open Action Items All 5 min Commissioning Schedule Bohn 10 min Augmented Recirculation/Lasing Procedure Douglas 30 min New Issues All 5 min
This Week's Attendees
J. Bennett, G. Biallas, C. Bohn, J. Boyce, A. Cuffe, D. Douglas, A. Grippo, K. Jordan, L. Merminga, G. Neil, M. Shinn, R. Walker, B. Yunn
Closed Action Items
None.
Items of Discussion
According to the updated plan for refurbishing the gun, we will be able to pull beam off the gun on Friday, 18 Sep 98. The basic plans for the week of 14 Sep are to high-voltage process the gun, do all possible hot system checks without beam, and (hopefully that Friday) restore the injector setup with the gun operating at 350 kV. Commissioning activities would then resume in earnest on 21 Sep, with the principal focus on high-power lasing with energy recovery. Activities that do not contribute toward that focus will be deferred, with the exception of trying to get initial data on CSR during owl shifts.
Concerning CSR experiments, the plan is to see if there is blatant emittance growth generated in the first recirculation bend. If so, parametric studies can begin based on measurements of rms beam properties in the vicinity of the wiggler. If not, careful setup of the injector may be necessary in that we will then need to know with higher confidence the phase space of the beam in the wiggler region to establish more accurately the initial conditions for simulations. For example, we would probably need good phase-space measurements at the injection point of the cryomodule (with Multislit #2 and Happek #1) as a benchmark of the beam dynamics.
Concerning our inability to date to do measurements at the injection point, it was suggested that there may be a problem with unwanted steering from MDU1F01 in that adjusting the colocated trim coil MDU0G00 has been seen to make a difference in the slit pattern achieved with Multislit #2. Consequently it was decided to add another trim magnet just prior to the injection point; G. Biallas has spare trims and will install one. This task has been added as a MUST to Walker's list.
The "kilowatt-related" installation/maintenance task list maintained by R. Walker has grown longer and was prioritized to reflect the "MUSTs". L. Merminga asked that the rationale for NOT highlighting the two magnetostrictive tuners as MUSTs be documented: the indigenous tuners have been verified to work quite well with 1.1 mA cw beam to the straight-ahead dump, and we know from our last runs that beam loss in the cryomodule was present. So, the fundamental need is to clean up the quality of the recirculated beam. However, if it is possible to ready the magnetostrictive tuners during this shutdown, then of course the task should be done.
As mentioned last week, everyone will need to work in a unified fashion if we are to achieve kW-level operation expeditiously. This means, for example, sticking to procedures, transitioning smoothly from one shift to the next, and respecting configuration control and decisions on "golden" machine settings. Consequently, for example, there is a need for buy-in on at least the Injector Checkout Procedure and the augmented Recirculation/Lasing Procedure before we resume commissioning.
G. Biallas presented his revised Injector Checkout Procedure. It looked good, with the only points of contention being (1) how to distinguish a "good spot" on viewer ITV0F04 (we will use a view foil to overlay on the monitor screen), and (2) whether to use cresting or the injector BPM to check cavity phases (we will use cresting and, in case of problems, revert to the Injector Setup Procedure that invokes the BPM).
D. Douglas will present the augmented Recirculating/Lasing Procedure next week, but gave an overview of some of his recent transport findings. In particular he finds that the presence of any residual nonlinear optics (specifically quadratic, or T_566, contributions) parabolically distort the longitudinal phase space at the wiggler, and this distortion sets up a pronounced energy spread at the energy-recovery (1G) dump that needs to be compensated (with, e.g., the sextupoles). This is something that won't show up in our PARMELA simulations because the code only does linear optics. Douglas, Yunn, Bohn, and others will be meeting in off-line discussions to consider the implications for the transport settings.
New Issues
See discussion above.
New Action Items
See discussion above.
Old Action Items
Procedures in Work
Procedures Needed for Recirculation
Unfinished Subsidiary Tasks for Phase Space Metaprocedure
Task Principal
---- ---------
I. Stabilize Drifts in Drive-Laser RF Phase Walker/Fugitt
II. Calibrate RF Gradients
A. Buncher Yunn
B. Cryounit Cavities (fix control screen) Merminga/Krafft/Yunn
C. Cryomodule Cavities Merminga/Krafft/Yunn
III. Reconcile Methods for Setting RF Phase Merminga/Krafft/Yunn
A. Buncher Cavities
2. Minimum bunch length/time of flight
B. Cryounit Cavities
1. Transient phasing
2. Cresting
3. Time of flight
IX. Complete Diagnostics Procedures and Users' Guide Krafft/Piot
A. M_55 #1, #2
B. Happek #1, #2
C. BPMs
1. button calibration factors
2. rotated MEDM spike charts
3. difference orbit data acquisition script
D. Multislit #1, #2
E. Quad/Viewer (at Wiggler, after Wiggler)
F. Multimonitor (at Wiggler)
G. SLM/CSR
H. Zero Phasing
I. Momentum Spread (Injector, Linac Pre-Wiggler, Linac Post-Wiggler)
J. Energy
XIV. Laser Turn-On Procedure Benson