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Tracker Magnetic Field concerns

Tracker Magnetic Field concerns. Craig Macwaters – STFC MICE CM34 at RAL. Step4 – Field in AIR at beam height (1.67M) Cryos in the range 400 to 1500 Gauss, about top of the AFE PCB EMR, TOF, Quads need refining. (Looking up to Q9). Field in AIR x-sect, upstream cryo z=-6.25M. ~600G. CH.

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Tracker Magnetic Field concerns

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  1. Tracker Magnetic Field concerns Craig Macwaters – STFC MICE CM34 at RAL

  2. Step4 – Field in AIR at beam height (1.67M)Cryos in the range 400 to 1500 Gauss, about top of the AFE PCBEMR, TOF, Quads need refining

  3. (Looking up to Q9) Field in AIR x-sect, upstream cryo z=-6.25M ~600G CH Turbo Lid CCG ~400G ~250G PSU

  4. Trying to get idea of flux in items… Example 10x10x10cm steel block in cryo location There are so many caveats to this that I should probably not show it but…You can see flux in steel block is approximately 3 to 7x that of surrounding air.Remember – this is an 8Kg block, it is very small. It is not like a psu which could be same ferrous mass but 40x volume. It is also heavier than the ferrous mass of the smaller objects. Maybe next step is to look bigger volume and smaller mass. See how compares

  5. Wiener AFE PSU • Wiener spec limit at 250Gauss, calculated field in air ~250G, but... • What is impinging field once the ferrous content is added to model? • Once we know field this will inform shield thickness. 5mm/1mm? • Mechanical design to fit shield within stand or make integrated soln. • Will require testing in typical field. Helmholtz/AFC/SS? • Look at costs of shielding vs. possible use of Wiener MARATON range • MAgnetism and RAdiation TOleraNt, Magnetic field tolerant to 1300G

  6. Cryostat cold heads • Sumitomo : Max 350G due to motor loading • Ideally much lower, like 50G • Model shows 600G just as air in this region! • Will need local shielding covering motor • Shielding the displacement shaft is the million dollar question! If this is a problem this will cause increased piston wear and require more regular servicing • Shield motor then look at shaft – monitor current in motor drive – increased torque • Mike G thinks will increase the heat load – diminish effectiveness of cooling

  7. 2 x Half cylinder shield? Flow Rtn. Elec.

  8. Lid Heater Box • Steel box with relays and 24V PSU • Area ~300G in air, • Relays unreliable 13 to 30G (ITER) • Looking into moving or shielding • Move - Extended heater element and thermocouples • Shield – steel box might help? • Items mounted on case will be at risk, move sensitive electronics well inside volume.

  9. Field in AIR at Turbo pump height (~250G)

  10. Cryostat turbo pumps • New Leybold SL80 CF63 turbos x4 • Limit 50G radially. In area ~400G in air • Vishal and DL vac group looking into this soln. • Spoken to Leybold who have contracted out tolerance analysis and shielding design to K.I.T. • Vishal visited, got lots of good info • Will provide operational guarantee • ∙ Shut off valve - Pneumatic

  11. K.I.T. Helmholtz pair test system • Edwards nEXT400 shield

  12. Turbo controller • Leybold TD400 turbo controller • Operating limit 150 Gauss • As standard next to turbo, so 400G air • Easiest to move away in a rack • Put with associated AC/DC PSU • Official 5M cable limit, • Got 8M but with no guarantee • Where would it go as Tracker rack might be just a bit further away. Split rack? • Need to do some pump tests, prove ok? • If can’t accommodate or operate from distance then shield box

  13. Cold cathode vac gauge • MKS I-Mag vacuum gauge used on cryo insulating vac • Field in air ~400Gauss, what’s this with ferrous content in model? • Ben at DL did some basic tests and quickly demonstrated that the reading was effected in a field. • Dropped at least decade at 0.3T • Need to do analytical tests that • are relevant to the field in area • Investigate if steel can shield will • effect performance? 60mT itself • Change from Inverted magnetron • type to traditional penning?

  14. AFE PCB transformer • Pulse transformer using ferrite toroid • Tested to 800 Gauss, in area ~1000G • Most likely requires a mu-metal can • Planning active test in higher field • Evaluate effectiveness of sample cans

  15. Compressors will now go on west wall Other tracker items Control racks x2 Remember a shielded rack will look a lot like this and have practically no access inside the shield box. Limited cable lengths. 10M VLSB. 30M for He lines. Rtn pressure drop, stall

  16. Tr1? Tr2? Possible new position of tracker racks : Ovals show a 7M reach from both cryo pairs Tr2? Tr1? Tr2? Tr2? Tr1? 7M ovals allow a further 2.8M for vertical drops. Making 9.8M total for AFE backplane to VME crate for VLSB cables.

  17. Tracker rack1? • Linac shield wall is steel loaded concrete • Approx 15% attraction of steel • So stuck between shield wall and that! • Need to model before get too excited

  18. More tracker items • Backing pumps. We were going to change to “Global” pump system but that’s now on hold, so... • We will likely need to fall back to the local pumps that are diaphragm type. Have been informed that these are probably ok but will need to check. • Vesda smoke detector has alarm relays (amongst other things) and will need to be piped up further away • UKUS transformer for lid heater box. Design out? • In total we have 14 tracker items we need to take action on!

  19. The way forward... • We need to get the cryostat items into a sub-model that can handle finer feature size (25mm on main hall model at moment) and assess the predicted fields. • We need a test facility (or at least regular access to one) to measure item sensitivities and then evaluate the effectiveness of the shielded designs. This will need a considerable amount of test effort, we cannot just install them and cross our fingers and hope for the best. • We will need a considerable amount of engineering effort to design shields to integrate with existing services and equipment. • Understand that the model produces results that are not utterly accurate. We have to approximate ferrous masses, item sensitivities, materials, shapes & sizes etc • Saying all that, I’m starting to think the modelling will be difficult for items like the lid heater boxand turbo. Ok for Wiener PSU and I’m unsure about the CCG and cold head. I feel we can't delay anymore with starting to design shields. We need access to a field which is typical of the area, typically 250 - 1000G and then put the items under operation in it and see if they work with a certain shield. • Do we have enough people and budget to deliver the magnetic shielding on time?

  20. 1xCryostats services Turbo control cable (5 or 8M max) 24V for turbo controller Backing pump mains Weiner interlocked mains Auto shut-off vac 24V Lid heater contacts 8 x green RG58 time & trig cables 4 x VLSB (Rubinov 12M max?) Blue RG58 1553 cable 5 x White Oxford temp sensors (max?) Weiner permanent mains Lid heater mains 110V ac MKS CCG gauge (max?) RG58 Weiner PSU enable Gas flexi for He cassettes 2 x 30mm braided hoses (30M max) 1 x 10mm power for cold head

  21. Ferrite Bsat 3000-4000GMuMetal 0.6TSteel 1.5TPower Inverter

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