Free Electron Laser Commissioning Meeting

Friday, 27 Feb 98
Recorder: C. Bohn

Next Meeting


Date: 6 Mar 98
Time: 0845-0945
Place: FEL Facility Break Room

Agenda for Next Meeting


Item Person Responsible Time ---- ------------------ -------- Status of Open Action Items All 5 min Status of Gun Legg 5 min Status of Commissioning Preparations Bohn/All 10 min Configuration Control Revisited Bohn 20 min Scheduling Bohn 10 min New Issues All 5 min Agenda for next week All 5 min

This Week's Attendees


S. Benson, G. Biallas, C. Bohn, D. Douglas, F. Dylla, D. Engwall, A. Hofler, K. Jordan, G. Krafft, R. Legg, L. Merminga, D. Oepts, P. Piot, J. Preble, M. Shinn, T. Siggins, R. Walker, B. Yunn

Closed Action Items


Items of Discussion


There was considerable and protracted discussion about the need for resources to do various tasks ranging from installation through commissioning/operations. F. Dylla requested that people give him direct and specific input about their needs so he personally can work them out. C. Bohn will likewise take immediate action and do everything possible to meet needs that are concisely and unambiguously defined with appropriate justification. The Accelerator Division as a whole is short-handed given the totality of its active projects. Consequently, as a matter of principle, resources need to be leveraged based on sound rationale.

Likewise, there was considerable and protracted discussion about the utility and nature of FEL training classes. The bottom line is that there are several layers of training, ranging from high-level introductory overviews (what is going on now) through the development of operator handbooks (the ultimate goal that is generally unachievable at present in view of the embryonic status of the FEL Program). Training will evolve as commissioning moves forward. Meantime, Bohn will keep taking steps to relieve undue stress from "novice" operators (e.g., FEL scientists and engineers) and ease in CEBAF operator support as it becomes available. D. Douglas urged everyone to be patient.

FEL Training, Part II, is moved to Thursday afternoon, 5 March, to avoid conflicting with the Division Group Leaders' Meeting planned for Monday afternoon. Bohn sent the agenda out this morning via e-mail.

R. Legg summarized the status of gun refurbishment. T. Siggins finished polishing the ball. The stainless steel shield for the getter pumps is in fabrication at a local contractor and will be delivered either late today or early tomorrow. It will likely be cleaned over the weekend and installed early next week, after which the gun will be buttoned up and baked. Legg and Siggins worked out a detailed plan for readying the gun for operation. Bottom line is that we project gun operations to resume on swing shift Sunday, 15 Mar 98.

An immediate impact of the gun delay is that we need to restructure our commissioning plans after turn-on to expedite GEN target irradiation. Consequently, we will run tune-up beam to the straight-ahead dump as quickly as possible, then insert the target chamber. Presumably installation of the GEN target will occur on or about 23 Mar 98, with deinstallation at the end of that week. We will defer all 60 pC setup until after the GEN targets are prepared.

There has been a general slippage in various installation tasks due to higher-priority needs on CEBAF. A plus in the gun delay is that the optical cavity might be completed by lock-up (provided modest Laboratory support can be brought to bear on related installation tasks), as will the MPS and probably installation of the "real" air-core correctors. Therefore, following GEN, we can go after first light unabated (unforeseen technical difficulties notwithstanding).

P. Piot presented results of his PARMELA "checkout" of the two multislit transverse-emittance diagnostics with the latest injector settings for 60 pC. His very nice analysis shows clearly the performance and accuracies we can expect from these devices when we use them for parametric studies and as monitors of injector performance. Piot's basic conclusions are the following:

New Issues


There is concern about whether and how the electro-optical cells in the drive laser should be integrated into the MPS. The bias on the EO cells is < ±100 V. Were the bias power supply to fail, the result would be a strong jump in current and ghost pulses. Many other details seem to be potentially involved, and so the matter needs off-line resolution (see "New Action Items").

New Action Items


Old Action Items


Procedures in Work


Emittance Growth from CSR

Thread Beam around Machine, Top-Level           Douglas, finalize 6 Mar 98
RF Stability during Energy Recovery             Merminga, 6 Mar 98
MPS/BLM Checkout for First Light                Jordan, 13 Mar 98

(Note:  The highest-priority item here is the procedure for MPS/BLM
Checkout for First Light!)