Free Electron Laser Commissioning Meeting

Friday, 31 Oct 97
Recorder: C. Bohn

Next Meeting


Date: 7 Nov 97
Time: 0830-0930
Place: FEL Facility Break Room

Agenda for Next Meeting


Item Person Responsible Time ---- ------------------ -------- Review of Minutes/Errata All 5 min Scheduling Update Bohn 15 min Progress Report on Injector Commissioning Legg 5 min Schedule/Requirements for GEN Target Prep Boyce 10 min Procedure for Threading to First-Light Dump Douglas 15 min New Issues All 5 min Agenda for next week All 5 min

This Week's Attendees


S. Benson, G. Biallas, J. Bisognano, C. Bohn, J. Boyce, D. Engwall, G. Krafft, A. Grippo, R. Legg, R. Li, L. Merminga, P. Piot, Q.-S. Shu, R. Walker, B. Yunn

Addenda/Errata to Previous Minutes


None.

Items of Discussion


C. Bohn presented the latest shift schedule for discussion, with emphasis on the rationale for the next two weeks. The two-week scheduling boards are in preparation and will be ready imminently in the FEL Facility Break Room. (Note: As of this writing, one has already been prepared.) They will be used to indicate shift tasks, and will be maintained and updated weekly. Some discussion ensued about the need to keep people informed of the specific tasks attendant to their shifts. Plans are to do this not only by way of the aforementioned boards, but also via e-mail. R. Walker was slated to e-mail FEL shift plans today. The desire is to handle scheduling matters in the same way as is done for CEBAF, although there are complications in that the FEL is now just entering commissioning, whereas CEBAF is operating. Nonetheless, we will try.

R. Legg and C. Bohn presented this week's injector commissioning highlights:

R. Legg discussed the procedure for setting up the straight-ahead dump. A 7cm x 7cm spot is required at the dump face to avoid melting it, and it is generated by rastering the beam. He calculated that, given a 1.1 mA, 2.4-mm-radius beam, the time to melt the dump face was 30 ms, representing the worst-case scenario. Therefore, the FSD interface for the raster should be required to respond in less than 3 ms. The FSD system can, in fact, respond much faster, but the trouble occurs in designing a circuit to decide if the AC power to the magnet is just going through the zero crossing or has failed. This is programmed in K. Jordan's I&C package. A second issue is inductive heating of the vacuum pipe. He mentioned we might want to insert a ceramic break in the dump line with correctors mounted over the break. It might be necessary to use an aluminum chamber. Legg will contact Chen in Hall C for input on these matters.

It was noted in subsequent discussion that the air-core correctors for the dump line (and for the linac in general) may not be available at the time we will be ready to take tune-up beam to this dump. Consequently, G. Biallas will check to see if spare CEBAF air cores are available, and Bohn will ask D. Douglas to assess whether CEBAF air cores would suffice for commissioning with tune-up beam. These tasks are necessary to enhance our confidence in being able to take tune-up beam to the straight-ahead dump before Christmas to get ready for preparing polarized targets for the GEN experiment. (Aside: J. Boyce remarked that he thought the target chamber would not be ready for installation until January, but he will check and report next week on this as well as electron-beam requirements for target production.)

Piot reported that the quad-scan emittance software is complete and ready for testing. He needs the model server, but has no information on its availability date. Bohn will contact S. Witherspoon for information.

New Issues


None.

New Action Items


Old Action Items


Procedures in Work


Cryomodule Setup

First Light Setup



Emittance Growth from CSR


Thread Beam around Machine, Top-Level           Douglas, 1 Dec 97