Target Meeting: 8th December 2010, 14:30

Present: JT, KL, PH, PS, EO, CB, JL, GB, BS

1. Review of Actions

         Date of target workshop. This was decided to be Tuesday 21st December, from 11:00, after the target inspection. KL to invite David Findlay, and contact Rose to book room.

2. Review of running in R78: PH

         Results from last run of T2.4 posted on Sheffield web site. In total (3 runs) 1M pulses; very little dust, no sign of wear, but occasionally stuck during capture. Sometimes freed spontaneously. PH to produce note on performance.

         New target T2.5 installed yesterday, with smaller land on anti-rotation face, so corners not able to dig in. Indications of minor wear after 20 hours running (similar to T2.4).

         Decision not to leave running over Christmas holidays. Stop for inspection on 21st Dec., resume in New Year. PH to contact AH to check pumps can be left on.

3. Progress on mechanical design and fabrication

3.1 Target Assembly: JT

         Lower shaft with company for spark erosion. JT will chase up. Will need shafts with integral lower stop quite soon.

3.2 Magnetic Measurements: BS

         Measurements of T3 performed, with more reliable arrangement. Probe flipped 180, measurements repeated and values averaged. From radial field, magnetic centre is displaced 24 m in x and 200 m in y, consistent down the bore. This appears much better than for T2, though the measurement method is not identical.

         Discussion followed on the merits of displacing the hole in the bearings to match mechanical and magnetic axes. BS agreed to measure the field symmetry about the observed centre, before a decision was made.

3.3 Stator Development: GB

         GB had circulated a summary of the useful meeting held at DL on 30th November. The (longer term) possibility of extending the stator to 36 coils had been raised; the pitch should remain at 3 mm; 5 windings per layer was favoured; square section wire 0.51 mm including insulation (~0.44 mm conductor) would imply increased voltage. The maximum temperature and estimated radiation exposure are needed to define the potting.

         More compact turns mean that the fins can be less deep, improving mechanical stability. Recesses for wire tails would be needed in the cooling jacket. JT reported that test machining had started, but there were problems keeping the fins in place.

         More modelling is needed, to determine performance with silver or copper conductor, changed coil geometry etc. Should this be in-house, or do we need Vector Fields?

         An aluminium core would improve thermal properties. Are there problems with machining, or vacuum issues? Should a dry nitrogen jacket be fitted to allow coolant at lower temperatures without condensation?

         Further discussion is required at the Target Workshop

3.4 Permanent Magnets: PH

         We should finalise the outer diameter at the target workshop. Otherwise, the design (ceramic washers, soft magnetic core) should not be changed in the next iteration.

4. Target Electronics & DAQ: PS

         Schematics for daughter boards are complete. They should be sent for manufacture before Christmas.

5. Target Paper: CB

         No developments

6. Next Meeting

         Target meeting 9:00 Wednesday 15th December.

         Target workshop 11:00 Tuesday 21st December, at RAL.


Summary of Actions

         KL to invite David Findlay to target workshop, and contact Rose to book room.

         PH to produce note on performance of T2.4.

         PH to contact AH to check pumps can be left on over Christmas.

         BS to measure the field symmetry about the observed magnetic centre.