1. Production Solenoid Region James L Popp Idaho State University FNAL - August 01, 2007 Mu2e Collaboration Meeting

2. 07/29/07JLPopp Mu2e2 Overview: PS Main Features Linearly graded solenoid magnetic field: 5.0 – 2.5 T : Realistic MIT field maps are used in GEANT simulations of all of baseline design – B = 5.0 T at upstream end of muon beam 8 GeV primary proton aimed upstream of the muon beam Water-cooled pion production target : MECO-TGT-03-001V1.01 Water-cooled heat and radiation shield : MECO-TGT-02-001V1.07 – Minimum bore radius: 25 cm Upstream muon beam vacuum closure : No Ref. Design exists DS TSd TSu PS

3. 07/29/07JLPopp Mu2e3 Design Software Tools Particle physics simulation –GMC (Generic Monte Carlo) based on GEANT3 –Nearly every detail of MECO (baseline) simulated here Heat Transfer –CFDesign particularly good for turbulent conditions ANSYS –Thermal and Mechanical Stress analysis Opera –Magnetic field calculations

4. 07/29/07JLPopp Mu2e4 Production Solenoid Region Vacuum closure plate located in low B-field region –Not shown: p beam exit vacuum window, PS+TSu vacuum port, target port –Dave Phillips at the AGS has drawings Heat & Radiation Shield Production Target Proton Beam Vacuum Closure Extension

5. 07/29/07JLPopp Mu2e5 Production Target: Design Considerations Goal: Maximize  - that lead to stopped muons in the DS target Compact to avoid  - re-absorption: minimize target and support –Mass & Geometric profile Maximize baryon density: –High atomic number –High mass density High thermal conductivity Insensitive to mechanical vibrations Target & cooling system –Minimize operating temperature & stresses –Stable & safe operating methods Assume worse case: –Steady state operation @ maximum instantaneous power –100 kW beam: 4x10 13 8 GeV protons for 0.5 sec every second Energy deposition: 9500 W instantaneous power

6. 07/29/07JLPopp Mu2e6 Target Operating Temperature Radiative cooling: Tungsten rod –High operating temperature –Single W rod mechanically unstable Maximum: 3200 K – mechanically unstable –Slicing & slotting rod increase stability complicated geometry and supports –  - re-absorption Maximum: 2000 K Convective water cooling: Gold rod –Drastically lower operating temperatures –Turbulent water jet & single rod: flow = 1 gal/min –Target surface temperatures: Inlet pipe 25 cm: coolant 20 C < T(critical) = 200 C Outlet pipe 25 cm: coolant 70 C < T(critical) = 160 C Rod core maximum: 125 C Temperature beam direction R=4mm, L=16cm

7. 07/29/07JLPopp Mu2e7 Current Water-Cooled Design Pt, W, or Au cylinder: L = 16.0 cm, R = 3.0 mm Ti inlet & outlet pipes: 25 cm long, ID = 2.1 mm, OD = 3.2 mm Annular coolant channel: h = 0.3 mm Tapered inlet end reduces pressure drop across target Water containment shell: 0.5 mm wall thickness Fully mixed coolant: T(outlet) – T(inlet) = 36 K Cut-away side view inletoutlet beam direction highest temperature location

8. 07/29/07JLPopp Mu2e8 Target and Water Temperature Under Turbulent Conditions Heat transfer calculations for turbulent flow conditions demonstrate feasibility of the cooling scheme Target Center Target/Water Interface Water Channel Center 397 K 293 K Water Inlet Titanium Tube Inner Surface Target Core J.Carmona, R.Rangel, J.LaRue, J.Popp, W.Molzon Turbulence calculation - unstable flow - - local fluctuations - - solutions to N-S eqs - time averaged,  t - UCI:

9. 07/29/07JLPopp Mu2e9 Target Installed in Production Solenoid 0.5” service pipes Slot in heat shield: - key stone guide - positioning Simple installation: - robotic manipulation - no rotations need - total of 1 vertical & 2 horizontal translations required Opening in heat shield for p beam entrance Target rotated slightly off-axis to be optimally oriented for the beam

10. 07/29/07JLPopp Mu2e10 Target Cooling Test Stand Diagram Control: target geometry & flow rate Monitor: temperature & pressure - target inlet & outlet flows - reservoir - target surface Temperature probes: - thermistors - thermocouple Measurements of interest in heating tests: - power deposition in target - heat transfer coefficients target heat exchanger - target surface temperature - response times for power cycling

11. 07/29/07JLPopp Mu2e11 Target Prototype Tests Two right-turns Tapered end Water cooling effectiveness is being demonstrated via prototypes Pressure drop vs. flow rate tests completed First induction heating test completed Comparison of Prototype Data with HD Simulations Actual pressure drop is lower than simulations predict UCI: J.Popp, B.Christensen, C.Chen, W.Molzon

12. 07/29/07JLPopp Mu2e12 Principle: Excite eddy currents which oppose changing magnetic flux, to obtain heating via Apply AC current to coil wrapped around work piece (e.g., solid rod, billet,…): H 0 = surface magnetic field intensity Solid cylinder: Induction Heating Ameritherm, Inc.; http://www.ameritherm.com http://www.ameritherm.com Induction Heat Treet, Co.; Huntington Beach, CA - 20 kW, 175 kHz - 30 kW, 10 kHz Example: Tensile test for metals at extreme temperatures

13. 07/29/07JLPopp Mu2e13 Measured Power Deposition Solid rod: - R = 3.0 mm, L = 16.0 cm - Carpenter Technologies: High Permeability Alloy 49, 50/50 Fe/Ni Measured power deposited: - reservoir temperature rise - (outlet – inlet) temperature Approximately same result: 1450 W 264 W per K / unit discharge (gpm) Increase power deposition: - improve design –coil & water containment shell –Obtain better match load inductance & power supply Induction coil: - 152 turns/m - L = 23.6 cm, R = 3.8 cm - copper tubing: OD = 0.635 cm Power supply - Lepel 20kW unit - f = 175 kHz

14. 07/29/07JLPopp Mu2e14 Measured Target Surface Temperature Probe near max surface T position: - 1.9 cm in from outlet end - > 0.5 mm below surface T target - T inlet = 21.0 C Scaled to MECO: P MECO = 9500 W, (T target - T inlet )P MECO /P test = 138 C Good approx.: T surface = T inlet + 138 C To maintain non-boiling condition - raise outlet pressure - chill inlet water - increase discharge rate Annular water gap, h = 0.4 mm Flow rate = 1.0 gpm  P = 125 psi Skin depth:  = 0.018 mm - f = 175 kHz - relative permeability    T target probe : - probe radial position not critical - T core - T surface < 1 K

15. 07/29/07JLPopp Mu2e15 PS Heat and Radiation Shield Purpose: protect PS magnet superconducting coils PCLC: L = 554 cm Rin = 70 cm Rout = 75 cm

16. 07/29/07JLPopp Mu2e16 H & R Shield Design Parameters Energy deposition in cold mass: Steady state, P<150 W Instantaneous local heating < 25  W/g Inner radius limit: 25 cm (10 11  -stops/s) Shield heat load: 16 kW steady state No line of sight from PS target to any point in cold mass Copper and Tungsten Total weight > 40 tons

17. 07/29/07JLPopp Mu2e17 H & R Shield Prototype Design Basic unit: Annular assembly – trapezoidal elements Limit weight elements to about 200 lbs 16 trapezoidal pieces – Two assemblies bolted together – Cu: 12 cm thick & W 6 cm thick 5 Cu ring stiffeners = 3 cm thick 8 Axial rectangular beams –8 cm X 5 cm –Purpose: structural & cooling

18. 07/29/07JLPopp Mu2e18 H & R Shield Fully Assembled Water channel runs the length of each beam –forms a u-turn channel –1 cm diameter –water inlet and outlet Both on up-stream end –4 cm center-to-center Homogeneous water flow – T(out) -T(in) = 5 K at 3 gal/min – Each beam Maximum radial temperature change: 40 C

19. 07/29/07JLPopp Mu2e19 Target Heat Shield Protects solenoids from radiation load –Optimized to reduce total load on magnet cold mass to ~150 W (UCI) –Approximately 16 kW of power deposited –6.2 kW – red (PHW3) –Combination of copper and heavymet –Supported off PS cryostat inner wall Work on construction technique and water cooling mechanism –Structural and thermal analysis by Jon Hock (BNL -- UCI contract) w / CFDesign Study of activation levels by Peter Yamin (BNL) Thermal analysis by Jon Hock (BNL) Installation gantry concept by Jon Hock

20. 07/29/07JLPopp Mu2e20 Summary Realistic magnetic field maps in simulations –Expected to evolve with solenoid system design Target cooling system: – Thermal stress design calculations needed – Further induction heating tests needed: wider parameter space Under normal & failure conditions Test methods for responding to system faults –Beam tests Heat and Radiation Shield: –Further thermal and stress design calculations –Prototype construction and beam tests –Shield monitoring system Need design of PS vacuum closure –Generate Reference Design

21. 07/29/07JLPopp Mu2e21 Water Cooling: Lumped Analysis of Heating Cycles Simple calculations and hydro code indicate large heat transfer coefficient Characteristic response time is of order AGS cycle time Target may reach steady state T on each cycle Time-dependent turbulent hydrodynamic simulations required to fully characterize the time behavior and more precisely the maximum coolant temperatures: CFDesign – suitable computational tool

22. 07/29/07JLPopp Mu2e22 Steady State Temperature Distribution Water-cooled Target Coolant containment wall Target surface r z Water gap, 0.3 mm Target surface Target surface Axial position - z Zoom below Diffusion dominated heat transfer layer: 10-20  m Fully developed turbulence in about 7 gap thickness along length Re: 15000 - 30000 47 C Titanium containment wall Target core 397.6 K 293.1 K

23. 07/29/07JLPopp Mu2e23 Target Fully Installed: Cut-Away Wide View of Production Solenoid W.Molzon, J.Popp, M.Hebert, B.Christensen Target Beam entrance Solenoid coil packs Basic unit