# Presentation: 096015

## MECO Production Target Developments

**James L. Popp**
**University of California, Irvine**
**NuFact’03**
**Columbia, June, 2003**

## MECO Collaboration

**Institute for Nuclear Research, Moscow**
- V. M. Lobashev, V. Matushka
**New York University**
- R. M. Djilkibaev, A. Mincer,                     P. Nemethy, J. Sculli, A.N. Toropin
**Osaka University**
- M. Aoki, Y. Kuno, A. Sato** **
**University of Pennsylvania**
- W. Wales
**Syracuse University**** **
- R. Holmes, P. Souder
**College of William and Mary**
- M. Eckhause, J. Kane, R. Welsh** **

**Boston University**
- J. Miller, B. L. Roberts, O. Rind
**Brookhaven National Laboratory**
- K. Brown, M. Brennan, L. Jia,             W. Marciano, W. Morse,                   Y. Semertzidis, P. Yamin
**University of California, Irvine**
- M. Hebert, T. J. Liu, W. Molzon,             J. Popp, V. Tumakov
**University of Houston**
- E. V. Hungerford, K. A. Lan,                 L. S. Pinsky, J. Wilson
**University of Massachusetts, Amherst**
- K. Kumar

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## MECO Muon Beam Line at AGS

**Goal: 10****11 ****stopped ************  / sec **
**1000-fold increase in ******** beam intensity over existing facilities**

**High-intensity proton beam and high-density target**
**Target, cooling, & support: compact to minimize ******** absorption**
**Axially-graded 5 T solenoid field very effective at ********collection**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target Heating

**Target: High density cylinder, L = 16 cm, R = 3-4 mm**
**4.0*10****13****  7.5 GeV protons / sec from AGS**
**Slow extraction, 0.5 s spill, 1.0 s AGS cycle time**
**2 RF buckets filled: 30 ns pulses, 1350 ns apart**
**Total on-spill power deposition: 7500 - 9500 W**
**On-peak energy deposition distribution: **

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Production Target Cooling 

**Radiation**
** ****minimal material in production region to reabsorb ********’s **
** ****significant ****engineering ****difficulties to overcome**
- high operating temperature, Toperation = 2145 – 3000 K
-    - high thermal stresses
-    - target evaporation
-    - little hope of raising production rate beyond current goals
- low-density materials: manageable stresses; but extended complex shapes, difficult to support & can lead to excessive pion reabsorption
**Forced Convection w/ water as coolant**
** ****low operating temperature, T****operation**** < T****boil - water**
**   ****- negligible thermal stresses **
**   ****- hope for achieving greater sensitivity **
** ****minor impact on MECO sensitivity: cooling system absorbs ********’s**
** ****modest engineering difficulties handling coolant (water activation)**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Production Target Physics Simulations

- All with 3 mm OD inlet/outlet pipes

-   Large inlet/outlet

- 

- 

- 

**Small water channel & thin containment tube costs 5% muon yield**
**Inlet & outlet pipes and target radius should be reoptimized **

- Tungsten target

**Simulations of design parameters with GEANT3 indicate that both production target cooling methods can meet  MECO physics requirements**

**GEANT Simulations of Muon Yield**

- UCI: A. Arjad, W.Molzon, M.Hebert, V.Tumakov, J.Popp

- Radiation-cooled

- R = 3 mm, L = 16 cm

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Radiation Cooling: Lumped Analysis of Heating Cycles

**Tungsten cylinder **
**R = 4 mm**
**L = 16 cm**
**Long time limit:**
**W: T****melting**** = 3683 K**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Radiation Cooling: On-Spill Temperature & Von Mises Stress

**beam**** ****direction**

**C. Pai, BNL**

**Tungsten cylinder, symmetry 1⁄4 **
**L = 16.0 cm, R = 4 mm**
**Power distribution: gaussian **
**Thermal dependence: Properties W **

**Von Mises stress**

**Temperature**

**Region of maximum Von Mises stress, ********Yield**** = 20 Mpa or less**
**Dividing up target into 0.1 cm slices, slotting    &    to axis, spacing by 0.8 cm gives stability, but target size is unacceptable**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Current Water-Cooled Design

**Pt 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**
**In MECO:**

**Cut-away side view**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target Installed in Production Solenoid

**0.5” service pipes**
**Slot in heat shield: **
**   ****- guide**
**   ****- positioning**
**Simple installation:**
**   ****- robotic manipulation**
**   ****- no rotations need**
**   ****- total of 1 vertical & 2 horizontal translations required**
**Opening in heat shield for beam entrance**
**Target rotated slightly off-axis to be optimally oriented for the beam**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target Fully Installed: Cut-Away Wide View of Production Solenoid

**W.Molzon, J.Popp, M.Hebert, B.Christensen**

**Target**
**Beam entrance**
**Solenoid coil packs**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Water Cooling: Lumped Analysis of Heating Cycles

**Simple calculations and hydo 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 **

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Turbulent Flow in Annular Water Channel

** ****Worst case: steady state, 9500 W**
** ****Inlet water conditions**
** ****temperature****	****= 20 C**
** ****flow rate****	****= 1.0 gpm**
** ****velocity****	****= 10.6 m/s at inlet**
** ****Flow channel**
** ****length****	****= 16.0 cm **
** ****radius****	****= 3.0 mm**
** ****gap****	****	****= 0.3 mm**

** ****Design parameters**
** ****target pressure drop****	****= 127 psi**
** ****inlet pressure****	****= 207 psi**
** ****outlet pressure****	****=   80 psi**
** ****max. local water temp****	****=   71 C**
** ****max. target temp (Au)****	****= 124 C (core)**
** ****mean discharge temp****	****=   56 C**
**stopped muon yield****	****> 95% of**
**                                               ****rad. cooled**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Steady State Temperature DistributionWater-cooled Target

**Steady State Temperature Distribution****Water-cooled Target**

**Water gap, 0.3 mm**

**Zoom below**

** ****Diffusion dominated heat transfer layer: 10-20 ********m**
** ****Fully developed turbulence in about 7 gap thickness**
** ****Re: 15000 - 30000**

**47 C**

**Titanium containment wall**

**Target core**

**397.6 K**

**293.1 K**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target and Water Temperature Under Turbulent Conditions 

**Heat transfer calculations for turbulent flow conditions demonstrate feasibility of the cooling scheme**

- 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:

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target Cooling Test Stand Diagram

** ****Control: target geometry & flow rate**
** ****Monitor: temperature & pressure:**
**  ****- target inlet & outlet**
**  ****- reservoir **
**  ****- target (not shown)  **
** ****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**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Target Prototype Tests

- Two right-turns

- Tapered ends

**Water cooling effectiveness is being demonstrated via prototypes **
**Pressure drop vs. flow rate tests completed**
**First induction heating test completed, next test June 2003 **

**Comparison of Prototype Data with HD Simulations**

**Actual pressure drop is lower than simulations predict**

- UCI: J.Popp, B.Christensen, C.Chen, W.Molzon

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## Induction Heating

** ****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**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## 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: **
**   ****- more turns per meter**
**     ****(coil w/ two close-packed layers) **
**   ****- reduce OD water containment shell**
**   ****- consider using higher-power unit**

** ****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  **

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## 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**** = 7500 W,**
**  ****(T****target****- T****inlet****)P****MECO****/P****test**** = 108 C**
** ****Good approx.: T****surface**** = T****inlet**** + 108 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**** << T****target probe**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003

## What next ?

**Opera calculations: redesign coil for greater power **
**   ****- two layers of coil windings**
**   ****- reduce OD of copper tubing, etc.**
**   ****- evaluate using 20 vs 30 kW unit (higher current & lower freq)**
**2****nd**** heating test in June 2003 **
**   ****- improved sensor operation**
**   ****- higher power deposition**
**   ****- gap size 0.4 mm, run at higher flow rate**
**   ****- gap size 0.3 mm, run at various flow rates**
**   ****- more precise positioning for target surface temperature probe**
**   ****- characterize response time of target **
**Opera calculations: design coil for MECO longitudinal heating profile**** **
**Redesign water containment shell to improve pressure drop**
**More heating tests in July 2003**

- J.L.Popp, UCI                                              MECO Production Target

- June, 2003