Target Summary/Status Chris Densham STFC/ RAL Mu2e Target, Remote Handling, and Heat & Radiation Shield Review Nov 16-18 2015 1
Schedule for Target Program ID Task Name 2015 2016 M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N 1 2 3rd RAL Mu2e contract 3 Contract 3 phase 1 ‐ E misivity and surface characterisation studies 4 Negotiate specification & contract 5 Contract start date 6 Characterise W surface finish vs emissivity 7 Test rig mods for energy balance measurements 8 DC sample heating tes t ‐ Proof of principle for sample Emissivity diameter 9 Optimisation of sample on DC heating test 10 Characterisation & testing ‐ ca libration of instruments Geoff,Peter,Rig[1] 11 Emisivity measurements of bare W in energy balance rig measurements 12 Post ‐ test characterisation 13 Manufacture energy balance sample 14 Coat energy balance sample 15 Measure emisivity of coated sample 16 Continuation of fatigue life testing 17 Contract 3 Continuation of target condition tests Pulsed lifetime 18 Test to faiture under extreme conditions 19 Post test evaluation 20 Shaped sample manufacture 21 test Steve[75%] Post EDM treatments Phase 1 22 Piston head sample/further coating 23 re ‐ configure rig for fatigue testing 24 Peter[50%],Rig[1] Shaped sample pulse tests 25 W surface & coating R&D 26 Lase r‐etch finned test rods 27 Etching rods Steve 28 Emissivity measurement (optical method) Peter,Rig[1] 29 SiC coating Design & 30 CVD coating of samples 31 TGA oxidation tests 32 Adhesion/bonding/sectioning tests 33 emisivity measurement of Si coated sample (optical Silicon-Carbide coatings Test method) 34 Thermal cycling of SiC coated tube sample (0 ‐ 1500°C) 35 Long bakeout of SiC coated tube sample 36 Pulsed testing at elevated temperature ‐ S iC tube sample 37 Oxidisation tests 38 Source 'little wire' samples Vacuum/leak 39 SiC coat wire samples Otto 40 'Little wire'/oxidation tests ‐ ba re W 41 'Little wire'/oxidisation tests ‐ si coated W test 42 SiC sectioning Intermediate 43 Decision on radiation cooled target feasibility and spec. coating/surface 44 decision on cooling technology made 10/08 report 45 1st intermediate report 46 Meeting attendance 47 Start contract 3 phase 2 28/08 48 Contract 3 phase 2 ‐ C reep testing and thermal optimisation 49 Alternative coating testing 50 Consider alternative coating materials 51 Carry out oxidisation tests on iridium samples Alternative coating technology 52 Pulsed sag testing of shaped sample in Horiz. Config. 53 Simulations of bending stress (sample vs target) Peter 54 Manuf new shaped sample PDF lab 55 Redesign rig for horiz simple support contacts Geoff Contract 3 56 Geoff[50%],Workshop[50%] Manuf new parts for rig 57 Geoff,Rig[1] Reconfigure rig 58 Rig[1],Peter[8%] Carry out sag test program 59 Presentations ‐ s ummarise progress Phase 2 60 revie w ‐ F ermilab 61 High T creep testing of taret components Creep/sag 62 Target sag test 63 Design test rig and samples 64 Manufacture rig components tests 65 Manufacture test sample targets PDF lab[33%] 66 Sag test W 67 Sag test Lathanum doped W Design & 68 spoke creep test 69 Design spoke creep rig and test samples Creep/sag 70 Manufacture rig components 71 Manufacture spoke sampes (W,Ta, LdopedW) 72 Creep test of Tantalum Test tests 73 Creep test of W 74 Creep test of Lathanum doped W 75 Elevated T creep testing of springs 76 Design creep test samples Prototype 77 Manufacture test springs 78 Creep test of various spring materials Helium cooled Optimise + prototype 79 Optimisation of target end joints springs 80 Design & analysis 81 Prototyping Final target concept 82 He cooling study and outline plant spec 2 target mount system 83 2nd intermediate report 84 Decision on design principles Report 85 Meeting attendance
Target Research Status (I) • Emissivity measurements for tungsten – Operating temperature determined for plain target at 7.7 kW beam power ✔ – Micro-fins enhance emissivity (lower T) but questions over fatigue life ✔ • High T pulsed fatigue performance of tungsten test samples – Sufficient for > 1 year lifetime ✔ – Encouraging data at increased pulse intensity • Sag/creep tests – Tests underway – Available data does not cause concern – If there is a problem, design can be modified e.g. support from Airy points • Radiation damage of tungsten – high DPA rate, He, H2 production – c.10x faster rate than in ISIS targets, higher T may be better due to high diffusion • ‘Bicycle’ wheel target concept – Simple installation into HRS/ easy remote handling ✔ – Spoke manufacture ✔ – Spoke tensioning system (2 options) ✔ 3
Target Research Status (II) • Operating conditions of radiation cooled target vs requirements – Vacuum level of 1e-5 torr expected by vacuum group – Vacuum level of 1e-6 mbar known to result in minimal tungsten oxidation – Uncertainty on target lifetime for actual operating conditions • Oxidation -> contamination of HRS • Target coating to mitigate oxidation – SiC: strong, high emissivity coating (lower T), performs well at 1e-7 mbar • Coating rapidly degrades at 1e-4 mbar, not suitable as anti-oxidation coating – Ir coating: much less reactive than W at high temperatures • few µm layer achieved by sputter coating • c.100 µm required for evaporation/diffusion tolerance – CVD being investigated, promising • Backup options: convective cooling to eliminate oxidation – Water or helium feasible – ‘Back door’ kept open to incorporate cooling system 4
Helium cooled target proton beam : 8GeV 8kW 1mm sigma heat load = 588W helium mass flow = 1g/s max helium velocity = 356m/s pressure drop = 0.2bar max tungsten temperature = 368°C temperature variation per pulse = 58°C max von Mises stress = 10MPa stress fluctuation = 6MPa 5
Target research status (III) Convectively cooled back-up Radiation cooled Water cooled Helium cooled Material Tungsten Gold Tungsten Graphite (low yield) Ta clad tungsten c.5% pion loss c.1% pion loss Physics (yield) High temperature, Some chemistry No chemistry Chemistry poor vacuum (W/H2O) Operating High Low Low W properties W properties W properties temperature Graphite Au properties Water connections, Helium connections, Ease of remote handling pipes pipes None Known tech. Complexity, price Plant issues None? Δ T, activity Δ T, activity Diagnostics Ox. in poor vacuum Water activation Low activation Contamination OK in good vacuum Issues with leaks Low leak concerns /activation Experience, data Little data Data on Ta clad W Data on pure W Little gold data 6 No Yes Yes Upgradeability
Radiation cooled target schedule (2 year float) 7
Radiation cooled target schedule (2 year float) Mid FY Detail 2018 Design Manufacture Prototype Target Contract 4 Intermediate Full Target Report Prototype Thermal Testing of prototype Final Report Manufacture And Assemble Parts Contract 5 Ship to Manufacture FNAL 1 st Production Target 8
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