Next Meeting

Date: August 6, 1996

Time: 3:00 - 4:00

Place: Test Lab Conference Room

Attendees

P. Piot, D. Douglas, J.C. Denard, D. Kehne R. Legg, G. Biallas, K. Jordan, R. Walker and G. Krafft

Corrections to Previous Minutes

• J.C. Denard informed me that the 9 MHz micropulse frequency suggested for tune-up mode in the last set of minutes was not adequate for the BPM's to function. Instead the PRF for the micropulses will be 18 MHz and the macropulses will be reduced to 2 Hz to maintain the low average current.

Items of Discussion

• Dave D. reported on the 10/42 MeV magnet which had been suggested to phase the cryomodule. He presented 4 plans to accomplish this.
  1. Crest 1-2 cavities at a time and power the dipole at 1.4 to 1.5 times the design.
  2. Build new extraction chicane dipoles to bend a 42 MeV beam.
  3. Build extra dipoles to boost the amount of bending produced.
  4. Phase the cavites to crest and anti-crest.
     Because 2 and 3) required new magnet types to be designed, they were discounted and a combination of 1) and 4) will be adopted particularly since Leigh didn't have grave reservations about overpowering the dipoles by 40-50%. Dave will detail this design after his vacation and put it on the www.
• The possibility of simultaneous longitudinal/transverse measurement after the new ceramics are installed in November was discussed by D. Kehne. The experiment has several issues, it needs a small beam in the chopper to reduce the energy shear, and the use of Dave Engwall's smaller aperture will require the beam to be focussed to close to 100 um at the slit. The solenoid used to focus the beam has to be in front of the chopper or it will re-focus the beam and reduce the resolution on bunchlength, but by putting it in front of the chopper, the aspect ratio is about 5:1 and the focussing will be tricky. Dave will do some more calculations to verify the cavity power and focussing parameters. Geoff will work with him off-line to help firm up the mechanical issues in the next two weeks. There will be a meeting on just this topic next Monday at 3:30 PM in room A110.
• The cryounit pair are positioned to run at 12 MV/m and 9 MV/m. D. Kehne modeled the effect that assymetric powering of the cavities has on emittance. He reports that it is less than a 10% effect from the 8 mm-mR nominal for a 350 keV input beam.
• D. Douglas said that by the inclusion of one more of the 10 MeV chicane dipoles the dump can be designed to very good momentum resolution for phasing and a good place for an emittance measurement. Legg, Douglas and Krafft (only ones who showed) met to lay out the 10 MeV diagnostics. It was decided to use a QB quad to focus the beam on an emittance slit or to compensate for dispersion, followed by a slit, a gap monitor, the QB quads to blow up the beam on the dump face, the raster and finally an OTR viewer to look at the slit results and to verify the raster and blow up quads operation. Dave Douglas will pass the DIMAD deck to George Biallas for review and mechanical design.

New Issues

• The Transverse experiment has a three milestone schedule of Design, Fab, and Ready-to-Use. No dates,YET...
• Modeling of lower than 10 MeV injector to account for off crest phasing in the quarter cryounit. Kehne to look at by 10/1/96.
• K. Jordan suggested we plan to have a second gun running in the test lab for 18-24 months to act as a spare and do further gun tests directed toward the 1 um and UV FEL's. Court Bohn to investigate.
• D. Douglas has posted most of his technotes on the web for perusal and links to the FEL pages. Check for requirements and magnet information.
• D. Kehne talked to Uwe Hapeck about his student and he was very receptive to having them stay here and perform other experiments and work with the machine. Kevin says he thinks he has a way to pay for his room and board. This could give us a third experimenter for the 10 MeV test and ease around the clock coverage.

Action Items

A-37 	Assymetric powering of cryounit.	Kehne		complete
A-38 	meeting to discuss dump diagnostics	Krafft		complete
A-16     Average Current Measurement/Assess Far. Cup     Legg	complete
A-17      4-Channel BPM on the IRFEL         Bohn, Denard	complete
A-41 	Modeling of lower than 10 MeV injector	Kehne, Liu	10/1/96
A-42 	2nd gun for long term tests		Bohn		10/1/96

Action Items (assigned)

A-01	Update Drawing                                Bohn                weekly
A-02    Magnet Specifications Webbed                  Douglas
A-04    Unit gradient precision                       Bohn, Liu
A-05    Injector energy precision                     Douglas
A-06    10 MeV dump optics                            Douglas
A-09    Dump Instrumentation                          Legg               6/04/96
A-10    Back leg diagnostic placement                 Douglas
A-11   	Multifrequency CSR Measurements               Krafft             6/04/96
A-12    How should the path length be checked?        Krafft, Jordan     6/11/96
A-15    Commissioning Procedure                       Legg, Krafft       5/16/96
A-19    Web Documentation                             Krafft              weekly
A-20    10->42 MeV dump                               Biallas
A-21    Diagnostics reviews                           Jordan             6/11/96 
A-22    Beam dump and scaper design                   Wiseman            6/18/96
A-24    Beam loss                                     Bohn
A-25    Synchrotron Light Monitors                    Krafft
A-26    IR Camera Plan                                Neil
A-27    Autosteer Plan                                Bohn
A-28    Transverse Effects in CSR                     Li
A-29    Software Planning for Longer Term             Bohn
A-30    Burnthrough/Conflat Expansion                 Denard, Kloppel
A-32    10 MeV emittance Plan                         Bohn
A-33    FSD Plan                                      Mahoney, Legg
A-34    Consistent Linac phasing plan                 Yunn
A-35    simultaneous transverse and longitudinal      Kehne/Engwall	8/6/96 
A-36 	'bad' injection dipole/dump geometry.	      Douglas		7/30/96
A-39	report on ARR plan 				Legg		8/23.
A-40	post tentative commissioning strategy 		Legg		8/6/96   

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-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-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-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
P-37    42 MeV dump design and interlocking

Agenda for Next Meeting

         Item                              Person Responsible     Time
         ----                              ------------------     ----
*   Review agenda/corrections to minutes	Legg	         5 min.
 
*   New issues                                                  10 min
*   Simultaneous longitudinal/transverse tests	Kehne/Engwall   10 min
*   BPM can design	                        Jordan/Yunn      5 min
*   10 MeV Dump design                         	Douglas         10 min.
*   Agenda for next meeting		            All		 5 min.