Presentation on theme: "MICE Target Report Chris Booth (for target team) Sheffield 23 rd April 2009."— Presentation transcript:
MICE Target Report Chris Booth (for target team) Sheffield 23 rd April 2009
Chris BoothUniversity of Sheffield 2 Summary of 2008 (1) MICE target drive is linear actuator, synchronised to ISIS, driving target in & out of beam in ~30 ms. Intended to have two parallel systems, one in ISIS plus “demonstrator system” outside. ISIS target installed January 2008 –Commissioned March. –Beam-loss and particle production studied to optimise dip depth & timing. –Used to commission MICE upstream beam-line and detectors. –Over 190K pulses by December. –Reliable operation; reproducible behaviour. –“Incident” on 29 th November when target accidentally parked in beam and ISIS manually restarted several times. –Subsequently needed ~8 mm increased depth for same beam-loss. –Erratic behaviour on 20 th December; jammed on 21 st. –Removed from ISIS in January shut-down.
Chris BoothUniversity of Sheffield 3 Examination of ISIS Target End of target blade melted. ~8 mm of length lost. Collar (end-stop) loose on shaft. Shaft seriously bent. Slight damage to DLC coating of lower shaft. Interpretation? –Melting occurred in 29 th November incident. –(Note: Interlocks now prevent parking of target when frame lowered!) –Loose collar caused shaft to jam, and probably damage to coating. –Was shaft bent during removal? Or due to impact of jammed collar on lower bearing? –(Note: Collar was a “fix” due to incorrect end-stop dimensions!)
Chris BoothUniversity of Sheffield 4 Summary of 2008 (2) Demonstrator system in R78 –January target (almost untested) failed quickly with electrical breakdown. Improved coil testing and QA. Voltage supply changed from 0 & 220 V to 110 V. –Two new target drives delivered to RAL late July. –One ran in R78 – failed after ~340K actuations. –Serious damage to shaft & bearing surfaces. –Significant abraded material, though little fell through lower bearing. –Same stator had run with old shaft & bearings (same design) for >500K actuations in Sheffield without problem. –Earlier shafts with DLC coatings run >5M cycles. –Unclear why failed setup was different.
Chris BoothUniversity of Sheffield 5 Possible failure causes investigated Misalignment of bearings and shaft - no. Partial demagnetisation of permanent magnets causing non-axial forces - no. Distortion of coils causing non-axial forces - no. Dynamic or static distortion of shaft - possibly. –High speed camera showed large amplitude lateral motion. –FE modelling shows resonance near drive period. Poorer quality DLC coatings on shaft and/or bearings - possibly. –Surface finish (smoothness, cleanliness) is crucial. Thanks to many people (RAL, Oxford, commercial) for help with these studies!
Chris BoothUniversity of Sheffield 6 Conclusion of MICE Technical Board We should not produce more target drives without a major redesign. Target team expanded, including design effort from RAL (Jason Tarrant). Basic linear motor design remains the same, but all components optimised for better QA, alignment, surface finish etc. Revisions to target/shaft, bearings, stator body etc. No changes (at this stage) to coils, magnets, cooling, optical position readout, bearing coatings etc. Major design means a delay in preparing next target is inevitable.
Chris BoothUniversity of Sheffield 7 Target/Shaft Cruciform shaft was insufficiently stiff, difficult to machine with good surface finish. Jason designed cylindrical shaft: –Titanium (as old target) –Tubular lower section (same mass/length). Stiffer. Higher resonant frequency. –Solid upper section. Flat on upper section to provide alignment. –Ground for high quality (bearing) surfaces. –Shortened. Due to changes in stator housing. Reach into beam increased ~10 mm. –Target is continuation of tube, not paddle (again, same mass). Same particle production. Optimisation of production versus beam loss later (geometry, material). –Needs welded join between sections.
Chris BoothUniversity of Sheffield 8 Revised stator body Stiffer Rigid case takes tension off welded seals Bearing mounts machined in situ for accurate alignment.
Upper Bearing Design l Alternative bearing design Wedge & dowel for full x,y,z location of clamp Anti rotation Feature (rounded or flat bearing face options) Single piece main body Wire cut from single piece for accurate wedge fit Full bearing merges into section for anti- rotation M/C with block in place to prevent tool wander Clearance for vane (potential risk if adding vane later otherwise simpler bearing)
Chris BoothUniversity of Sheffield 10 Status & Schedule Design complete. Materials ordered or procured. Production of machining jigs etc started. Sample weld looks very good quality. Tests for shaft machining, centreless grinding etc in progress. Stator coil assembly underway (Sheffield). Two target assemblies (ISIS + demonstrator) due 22 nd July (plus spare). Test, then install in August ISIS shutdown. Running from 2 nd September.
Chris BoothUniversity of Sheffield 11 Target Control Microprocessor-based system currently in use very reliable but “expert system”. –Diagnostics difficult for non-experts. –Switches, LEDs, burning EPROMs, rather than user-friendly GUI running on PC. System at processor & I/O limit – impossible to add new features. Paul Smith (Sheffield) & James Leaver (IC) undertaking ground-up rebuild, using FPGA. –Integrate many elements (separate crates) on one board. –USB interface to control PC. –Auxiliary electronics on daughter cards. Initially mimic current functionality, later enhance. –Full configuration /control / status monitoring via PC. Intended to be ready for integration in ISIS in August – but a lot of work to be done!
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