Next Meeting

Date: April 16, 1996

Time: 3:00 - 4:00

Place: Test Lab Conference Room

Attendees

K. Jordan, J. Denard, C. Bohn, G. Neil, D. Douglas, L. Merminga, S. Simrock, L. Doolittle, B. Dillon-Townes, and G. Krafft

Items of Discussion

There were no changes to the minutes. No organizational issues were discussed. K. Jordan has tracked down a method whereby the meeting minutes can be published on the WEB. The minutes should be forwarded through e-mail to jenni@cebaf.gov. Krafft agreed to add jenni to the distribution list, and will send copies of the `back issues'. Kevin also agreed to make sure the minutes list starts, but at some point we will have to discus how the information is intelligently organized.

Action Items

A-01 No major updates for the main machine were proposed. Much of the more detailed work is proceding. On the Injector Test Stand, only the final design choice for the bend magnet needs to be made (A-19 below). Kehne will coordinate with Harwood and Sinclair and get this resolved.

A-03 No documentation confirmation as of 4/9/96.

A-05 Dave did not complete this task, but agreed to calculate the energy acceptance of the recirculation optics ASAP. Dave did report that the optics has been verified, including the wiggler's multipole effect on the beam dynamics, a substantial piece of good news.

A-08 L. Merminga reported on her recent simulations on beam loading in the single- pass and multipass configurations. She ran the 650 muA, 250 musec proposed tunup pulse and observed essentially no transient effect at 250 musec. The peak loading was 2 times 10 to the -3 at 50 musec after the pulse starts. The conclusion is that no feedforward is needed for tuneup mode. She has also started simulation work on the recirculation case, but feels uncertain about the actual reciculation phases. She separately has mentioned to the' recorder that perhaps someone should go through the machine `al la Neuffer' and make sure the phase sets are totally consistent. The recorder was unsuccessful in getting her to volunteer for this important task. Next meeting we will discus what needs to be done to get this resolved. Lia also felt that she would like to present her talk to the group for practice. This was scheduled for next week.

A-11 Krafft reported on the multifrequency CSR proposal calculations that he has done up to now. They consist of evaluating the form factor as a function of wavelength for the nuclear physics machine using PARMELA outputs of the phase distribution. The results indicate that capture phasing of order 0.1 degrees is possible and `gang' phasing of order 0.3 degrees is possible. The talk stimulated the question of whether such measurements might help on resolving the transient CSR questions. Krafft asserted that independent of the transients the form factor calculation will give the correct relative power levels as the bunch distribution changes.

A-12 No report

A-13 Bohn reported Yunn's impedance summary. The basic conclusion is that the wiggler will have an impedance effect smaller than some of the other sources in the line, so the first order question is resolved favorably. The estimates assumed the beam will travel within 100 micrometers of the wiggler center; it was felt that this would have to happen to get lasing anyway. He also reported that most of the power would be deposited toward the exit of the wiggler, of order 45 W. This was not deemed to be a problem. Also it was indicated that the accelerator is an impedance friendly device. The issue was declared closed; Bohn will forward the three summary tables to Neil with a summary. Yunn will write a final technote when the machine configuration freezes.

A-14 No final documentation report has occurred.

A-17 No final report was forthcoming, but a plan has been developed. Denard will present a final requirements list for the FEL BPMs next week. The following week we will decide whether to use the 4-channel electronics. Right now this looks very probable.

In the course of the week, two items were added to our list. The injector setup diagnostics look weak for the main machine, and G. Neil asked whether a substantial portion of the backleg quads can be run in series. The tenta- tive solution for the first issue was proposed by K. Jordan and discussed, namely to place an OTR viewer in the parallel straight right before the injector merge. There were no objections to this. A more thorough study is added to the pending list. The second issue was also added to the pending list.

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            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

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    Injector diagnostics in the main machine
P-16    Gang of power supply for backleg quads
P-17    Technote by Yunn summarizing machine impedance

Agenda for Next Meeting

          Item                              Person Responsible     Time
          ----                              ------------------     ----
*   Review agenda				    Krafft	  5  min.
*   Corrections to minutes from last meeting	    All		  5  min.
*   New drawing                                     Bohn          5  min.
*   Unit Gradient Precision                         Bohn, Liu     10 min.
*   RF issues in the IRFEL                          Merminga      20 min.
*   BPM requirements                                Denard        10 min.
*   10 MeV Magnets and Experiment Plans             Kehne         10 min.
*   Agenda for next meeting		            All	  	  5  min.