1 / 76

Field Mapping

1/70. Field Mapping. V. Blackmore CM38 23rd February 2014. 2/70. There is a lot of information in these slides, and not enough time to say it all. A lot of this will be revisited in future analysis meetings.

debra
Download Presentation

Field Mapping

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 1/70 Field Mapping V. Blackmore CM38 23rd February 2014

  2. 2/70 There is a lot of information in these slides, and not enough time to say it all. A lot of this will be revisited in future analysis meetings. I have added notes to most slides (if you download the .ppt version), so they should be understandable “offline.” As for now, we’ll see just how far we get...

  3. 3/70 Mapped Currents Contents Survey plots presented at CM37. Today: Coordinate systems Effect of the shielding plate Linearity of field with current Residual magnetic field Probe Jitter Hysteresis Magnetic axis fits 4 17 24 29 41 • Runs cover the above currents, plus: • 0A measurements (residual field) • 30A individual coil measurements (superposition) • With and without Virostek plate 48 50 A lot of data

  4. 4/70 Coordinate Systems Until the end of this talk...

  5. 5/70 The “Mapper” Co-ordinate System Mapper: Movement example video* • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video * “Spectrometer Solenoid” *Thanks to F. Bergsma “Upstream” end and Virostek Plate Hall probe card Probes numbered from 0 to 6 in order of increasing radius Probe “0” on axis “Conveyor belt” “Carriage”

  6. 6/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video

  7. 7/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Tick! In file for : Record probe number,

  8. 8/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Tick! In file for : Record probe number,

  9. 9/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Tick! In file for : Record probe number,

  10. 10/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Rotate! Tick! Start new file for : Record probe number,

  11. 11/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Reverse!

  12. 12/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Tick! In file for : Record probe number,

  13. 13/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Tick! In file for : Record probe number,

  14. 14/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Rotate! Tick! Start new file for : Record probe number,

  15. 15/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video Forward! etc. etc.

  16. 16/70 The “Mapper” Co-ordinate System Mapper: Movement example video • To avoid changing too many variables at once, all of the data (until it says otherwise) is in the “mapper co-ordinate system.” • No survey corrections (as described at CM37) have been applied. Mapper: Rotation example video • Each data “set” is taken over the same range of in the same number of steps, and similarly for • Each is recorded in a separate data file • I do combine these files • I do rotate , and keep (see “backup slides”) • is what the mapper reports Forward! etc. etc.

  17. 17/70 * Mapper m Mapper at this side The Shielding Plate Compare identical measurements with and without the shielding (“Virostek”) plate “Identical”: Same currents *Photographs gratuitously stolen from S. Virostek’s talk at CM36

  18. 18/70 Spot the Shielding Plate Let’s play • “On-axis” probe, plotting (i.e. ) w.r.t. mappers recorded position at 4 angles of • Measurements at 50% current, Solenoid Mode (will come back to linearity)

  19. 19/70 Spot the Shielding Plate Let’s play • 150mm probe, plotting (i.e. ) w.r.t. mappers recorded position at 4 angles of • Measurements at 50% current, Solenoid Mode (will come back to linearity)

  20. 20/70 Spot the Shielding Plate Let’s play • 150mm probe, plotting w.r.t. mappers recorded position at 4 angles of • Measurements at 50% current, Solenoid Mode (will come back to linearity)

  21. 21/70 Spot the Difference: Let’s play • is interpolated along the -axis • Compare at fixed -points • From the field changes quickly • “Noise” in this region probably due to rapidly changing field Probably due to rapidly changing field (?) mm mm

  22. 22/70 Spot the Difference (Again) Let’s play Field increased by shielding plate Would guess the centre of the shielding plate is here! T at mm T at mm Field decreased by shielding plate

  23. 23/70 Spot the Difference: Let’s play mm Probably due to rapidly changing field (?) mm

  24. 24/70 Field linearity With no shielding plate, field should belinear with current. With shielding plate, field may benon-linear with current

  25. 25/70 Without the shielding plate… • (Black) 100% current in Flip Mode • (Red) 80% current in Flip Mode • Scale up 80% measurements and compare…

  26. 26/70 Without the shielding plate… • (Black) 100% current in Flip Mode • (Red) 80% current in Flip Mode • Scale up 80% measurements and compare… • First impression is good.

  27. 27/70 Without the shielding plate… Scaled down field measurement Majority of differences are where field is changing T Scaled field is slightly larger (difference <0)

  28. 28/70 With the shielding plate… Scaled by 1.25 Scaled down field measurement T Larger difference at large This region was previously negative Majority of differences are where field is changing, now looks more systematic

  29. 29/70 Residual field We do have data sets that allow us to naively look at the residual field Q: Does the residual field change depending on the previous operating current?

  30. 30/70 Residual Field Measurements No intermediate measurements carried out between these pairs of data • Every day of measurements began/ended (or both) with a field map at “0A” • Can compare measurements at 80/100% field and 0A. • Still using “mapper co-ordinates” • Order of measurements does matter Intermediate Flip Mode runs (not interspersed with 0A data). Shielding plate removed 15th—16th June. Colour-coded dots are meant to help those viewing later

  31. 31/70 7th—10th June: On-axis probe only Previously at 80% Sol. Mode Ran at 80% Solenoid Mode, then turned everything off and took a well-deserved weekend break 0A, so line should be flat – but is it?

  32. 32/70 7th—10th June: On-axis probe only Previously at 80% Sol. Mode Scaled 80% SM measurements for general shape comparison only. Not very flat – but there are welds, which will be magnetic (hence suffer residual field). Possibly correlates with mapper carriage movement?

  33. 33/70 10th—11th June: On-axis probe only Previously at 3.6% Sol. Mode Ran at 10A (3.6%) Solenoid Mode, then went home for the night The next morning, at 0A

  34. 34/70 10th—11th June: On-axis probe only Previously at 3.6% Sol. Mode 3.6% SM scaled for shape comparison only Similar to before?

  35. 35/70 10th—11th June: On-axis probe only Previously at 3.6% Sol. Mode 3.6% SM scaled for shape comparison only Similar to before? Yes!

  36. 36/70 11th—13th June: On-axis probe only Previously at 100% Sol. Mode Now it gets interesting: After the previous slide’s 0A run, ran at 100% SM. The next day took a 0A measurement…

  37. 37/70 11th—13th June: On-axis probe only Previously at 100% Sol. Mode 100% SM scaled for shape comparison only Much flatter! More obvious when compared to previous 0A measurements… (Does make mapper carriage movement argument moot)

  38. 38/70 11th—13th June: On-axis probe only Previously at 100% Sol. Mode 100% SM scaled for shape comparison only The only thing that happened between and is a 100% field run.

  39. 39/70 19th—19th June: On-axis probe only Previously at 100% Sol. Mode 80% SM (no shielding plate) scaled for shape comparison only All bar consistent here : Several Flip Mode runs, shielding plate removed, then back to 80%SM followed by 0A measurement.

  40. 40/70 7th—19th June: On-axis probe only Shielding plate differences 80% SM (w/ & w/o shielding plate) scaled for shape comparison only

  41. 41/70 Probe Jitter What kind of error bars should we be imagining on the previous plots? Look at the “flat” regions of the 0A measurements and see what variation there is in probe readout.

  42. 42/70 Region of Interest: m Probe at 90mm sees more residual field that the others 180mm probe has a large spike here • Consider dotted region • Is approx flat in all 0A measurements • Should have a negligible residual field • Use , June 13th 0A measurement, as it is “flattest” • Compare with measurement from June 14th (not previously shown) • Calculate mean and standard deviation in this ROI

  43. 43/70 Mean Residual Probe at 90mm sees more residual field that the others • Mean residual is different after powering magnet • Only probe 5 (mm) is consistent with zero • Probe 3 sees consistently higher fields, but it should be consistent with other probes

  44. 44/70 Mean Residual • Mean residual are all consistent with 0 (including probe 3) • Noisiest -axis probes are 2 and 4 • Mean residual are all consistent with 0 • Noisiest -axis probes are also 2 and 4

  45. 45/70 Mean Residual • Mean residual are all consistent with 0 (including probe 3) • Noisiest -axis probes are 2 and 4 • Mean residual are all consistent with 0 • Noisiest -axis probes are also 2 and 4

  46. 46/70 Probe Jitter Comparison Composite of previous 3 slide’s plots

  47. 47/70 Probe Jitter Comparison • G • Exceptions are probes 2 and 4 in and • No measurements without SS present, so residual field effects are difficult to quantify • There are other ‘uncertainties’ to consider, but this is a start!

  48. 48/70 Hysteresis Q: Do we achieve the same field when we approach it from below the operating current and above the operating current?

  49. 49/70 Hysteresis • Ideally, requires consecutive four measurements with the shielding plate • 0% solenoid/flip • 80% solenoid/flip mode • 100% solenoid/flip mode • 80% solenoid/flip mode • We have 0%80%, and 0%100%, but do not have 100%80% • Mapping takes a long time • Time taken by shielding plate installation and removal • Judging by changes in residual field, likely there will be a (very) small hysteresis effect • Should make this measurement when mapping final SS

  50. 50/70 Finding the Magnetic Axis (First pass) The mapper moves about by ~ 1mm in (x,y) as it travels through the magnet To first approximation, ignore this movement and use mapper co-ordinates to get an estimate of the magnetic axis

More Related