Target discussion, 15Oct08, 09:00

Present: WL, SY, JT, AD, CB, RN, AN, KL, EMcC

1. Review of actions:

• PH: Take damaged shaft to TechVac to show them failed coating and to solicit feedback.
  Stands.
   
• KL: Post on WL 2007 FEA document on WWW site.
  Done.
   
• AN: will contact EMcC to see when he is needed.
  Done.
   
• AD: Consider effect of target orientation on beam loss
  
  AD has simulated the beam loss under two conditions.  Each has a target 10 mm in length and 1 mm thick inserted such that the tip is 27 mm from the centre of the ISIS beam pipe.  This corresponds to a 'dip depth' of 46.9 mm.  This dip depth is within the range of dips used to date in MICE running.
  
  In the first (plot) the long axis of the target is parallel to the ISIS beam direction.  In this configuration there is significant loss predicted in SP7 and a more moderate loss predicted in SP1.  By contrast, the second configure (plot) with the long axis of the target perpendicular to the beam axis predominantly produces beam loss in SP1.
  
  EMcC comments: where collectors are in straight 1 has become a 'hot' area.  For MICE it would be a problem to create a second 'hot' area.
  
  AD agreed to simulate beam loss with target parallel to extracted pion beam.
   
• KL: Contact MA to ask him to consider effect of target orientation in collection
  Done.
   
• AN/KL: Talk to CMacW to confirm him as 'lead' on magnetic measurement of stator coils (QA and present coils).
  AN.KL 'assume' that CMacW knows.  Action stands.
   
• CB: Talk to PH to ask him to 'lead' on QA for permanent magnets.
  Done.

2. Progress on magnetic measurements

• Stator: CMacW:
  
  Email from CMacW:
   
  • The new chiller is set-up and at the max Volts (31V) of the PSU I pull 7.5amps through the coil. At this setting I measure 60C on the thermocouples with the water at 10C.
     
  • Jim and I set up everything straight and we took a set of measurements from bottom to top of the target right down the inside bore wall. Only problem is looking at the results all we see is noise. We checked the hall probe with a big magnet and it was fine. What level of field would you expect us to find?
    
    PS and CMacW will continue to liaise on the stator magnetic measurement.
     
• Permanent: PH:
  
  PH has spoken with HN at Brunel.  It is possible that Brunel can contribute a multi-axis positioning devise.  In parallel equipment has been identified in Sheffield.

3. Progress on mechanical design: JT

• Propose to focus on bearings and coating materials in first instance.  Will look at damaged shaft and bearings when JT is in Sheffield tomorrow (Thursday).
• In addition, will look at shape of bearing and shaft.  Tolerances need also to be revisited.  Bearing position to be investigated too.
• JT has found sources on bearings in vacuum.  There may be some evidence that careful choice of alloy or coating may help in reducing the coefficient of friction.   It may be possible to use a 'nitride' coating without dis-assembling the bearing.
• JT has also found information on measurement of heating of bearing surfaces in operation.
• JT will check through meeting notes and discuss with EMcC today before visiting Sheffield.
   
• CB: Possible difference between Sheffield and RAL systems is that there is a foam base in Sheffield while the RAL system is rigidly mounted.  The differences will be investigated using the digital camera.

4. Progress on (dynamic) mechanical FEA: SY, WL

• See slides.
• Require to validate analysis with measurement (high-speed camera for example).
• Agreed:
  • Analysis indicates that during the redesign, care must be taken to eliminate lateral forces as far as possible by careful specification of alignment tolerances re-enforced by appropriate QA;
  • Since lateral forces will necessarily arise in fault conditions, the new design must cope with them.  A lateral force on the bearings of 1 N was assumed in the analysis and was felt to be a reasonable expectation.  The size of the lateral force will be confirmed by comparing the simulated oscillations with the results of high-speed camera measurements;
  • A measurement of modes of vibration on a 'vibration table' (available at RAL) will be included in the study of the present target shaft design and as part of QA of the redesigned target and shaft; and
  • AN agreed to contact the 'owners' of the vibration analysis setup at RAL.

5. Progress on magnetic FEA: PS

• PS will take OPERA 3D course.  No technical progress reported this week.

6. Discussion

Noted above.

7. Date of next meeting

29Oct08: 09:00 -- RAL/phone

8. AoB

• CM22: agenda:
  • CB: Overview and review of present target system;
  • JT: Discussion of mechanical redesign options;
  • WL: Discussion of dynamic FEA analysis;
  • AN: Discussion of plans for development of #2 target

Summary of actions:

• PH: Take damaged shaft to TechVac to show them failed coating and to solicit feedback.
• AD: Simulate beam loss with target parallel to extracted pion beam.
• AN/KL: Talk to CMacW to confirm him as 'lead' on magnetic measurement of stator coils (QA and present coils).
• AN: Contact the 'owners' of the vibration analysis setup at RAL.
• KL: Provide upload link for the next meeting.