bene/care frascati 14-17 november 2006 cj densham cclrc rutherford appleton laboratory solid target...
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BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Solid target studies in UK for T2K and for a neutrino factory
JRJ Bennett, S Brooks, R. Brownsword, O Caretta, CJ Densham, R Edgecock, MD Fitton, VB Francis, S Gray,
A McFarland, M Rooney, G Skoro* and D WilkinsUnderlined are those who have given talks at BENE06
C.J.Densham@rl.ac.ukRutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, UK
Except * Sheffield University, UK
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Solid target studies in UK for T2K and for a neutrino factory
Partial summary of BENE06 presentations: T2K target station beam entry window
Matt RooneyDesign and Computational Fluid Dynamic analysis
of the T2K TargetMike Fitton
Shock wave experiments for T2K and Nufact target materials.
Chris DenshamFluidised beds: a new idea for a neutrino factory
targetOtto Caretta
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
T2K Secondary Beam Line
DV
TS
BD
Beam Dump(BD)•graphite core in helium vessel
Target station (TS) •Target & horns in helium vessel •Helium vessel and iron shields cooled by water Decay Volume (DV)
•94m long helium vessel cooled by water•6m thick concrete shield
‘280 m’ neutrino monitor
50 GeV PS ring
Primary beam lineFast extraction
Kamioka
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
T2K Target area
Inner iron shields
Inner concrete shields
Support structure= Helium vessel(being constructed by Mitsui Ship. Co.)
Baffle Target and 1st horns2nd horns
3rd horns
Beam window
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
The T2K Beam Window
Matt Rooney
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Beam Window Assembly
Window Overview
- Double skinned partial hemispheres, 0.3 mm thick.- Helium cooling through annulus.- Ti-6Al-4V.- Inflatable pillow seal on either side.- Inserted and removed remotely from above.
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Helium cooling of beam window
He in He out
Titanium - 0.3mm
Titanium -0.3mm
Helium3mm Gap
Upstream
Annulus
Downstream
Helium velocity ≈ 5 m/sHeat transfer coefficient ≈ 150 W/m2K
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Stress Waves: effect of 8 bunches/beam spill
Stress wave development in 0.6 mm constant thickness hemispherical window over first 2 microbunches.
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
0.62 mm thick Ti-6Al-4V window - Constructive Interference between
bunches
-200
-150
-100
-50
0
50
100
150
200
0 1 2 3 4 5
Time from beginning of pulse (μs)
Stre
ss (M
Pa)
Von MisesHoopLongitudinal
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
0.3 mm thick Ti-6Al-4V window - Destructive interference between
bunches
-200
-150
-100
-50
0
50
100
150
200
0 1 2 3 4 5
Time from beginning of pulse (μs)
Stre
ss (M
Pa)
Von MisesHoopLongitudinal
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Important lesson: thicker is not always stronger!
• With a pulsed proton beam, window and target geometry can greatly affect the magnitude of stress.
• Be careful to check dynamic stress when changing beam parameters or target and window geometry!
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Design and Computational Fluid Dynamic analysis of the T2K
Target
Mike Fitton
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
RAL target design in the 1st Horn
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Helium cooling flow path
Matt Rooney’s initial calculations suggest this window is ok for pressure and shock.
Inlet Manifold
Outlet Manifold
Flow turns 180° at downstream window
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Animation of flow
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Velocity StreamlinesCurrent design
Previous design iteration
Optimised for uniform flow
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Velocity profile at downstream window
30 GeV, 0.4735Hz, 750 kW
Radiation damaged graphite
Optimisation for pressure drop and window cooling
Original Concept
Current RAL Design
•Pressure drop unacceptable
•No downstream window
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
30 GeV, 0.4735Hz, 750 kW
Radiation damaged graphite (20 [W/m.K])
Mass flow rate = 32 g/s
Steady state target temperature
Maximum temperature = 1009˚K = 736˚C
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Radiation Damage of Graphite
For a radiation damaged target a thermal conductivity of 20 [W/m.K] is used (approx 4 times lower than new graphite at 1000°K)
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
T2K graphite target stress wavesMax Von Mises Stress: Ansys – 7MPa
LS-Dyna – 8Mpa
Max Longitudinal Stress: Ansys – 8.5MPaLS-Dyna – 10MPa
Ansys LS-Dyna
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Shock wave experiments for T2K and Nufact target
material
Results from‘Shock Tests on Tantalum and
Tungsten’
- presented by Roger Bennett at Nufact06
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Shock wave experiment at RALPulsed ohmic-heating of wires to replicate pulsed proton
beam induced shock waves in materials- using ISIS kicker magnet power supply
current pulse
Material test wire
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
LS-Dyna calculations
for shock-heating of
different graphite wire
radii
G.Skoro,
Sheffield University
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Vertical Section through the Wire Test Apparatus
Current
Inner conductor of co-axial insulator feed-through.
Stainless steel split sphere
Copper “nut”
Current
Two graphite (copper) wedges
Spring clips
Fixed connection
Sliding connection
Test wire: Graphite (T2K) or Tungsten (nufact)
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Some Results of 0.5 mm diameter wire tests and ‘equivalent’ nufact target parameters
36-
48
24
Beam PowerMW
4.2x106
+PLUS+
>9.0x106
>1.6x106
>3.4x106
0.2x106
No. of pulses to
failure
1900
2050
1900
2000
1800
Max. Temp
K
23-
12.5
12.5
130
140
5560
5840
2.5Not broken. Top graphite connector failed.
23
6.2517064003Stuck to top Cu connector
23
12.510049003Broke when increased to 7200A (2200K)
Tungsten
Tantalum is not a very good material – too weak at high temperatures.
12.56030004Tantalum
Target diacm
Rep RateHz
Pulse Temp
.K
Pulse Current
A
Lngth
cm
Material
“Equivalent Target”: This shows the equivalent beam power (MW) and target radius (cm) in a real target for the same stress in the test wire. Assumes a parabolic beam distribution and 4 micro-pulses per macro-pulse of 60 s.
Equivalent Target
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Velocity Interferometry (VISAR) : to measure shock waves on material surface
Laser
Frequency ω Sample
Velocity u(t)
Fixed mirror
Beamsplitter
Etalon
Length hRefractive index n
Detector
Fixed mirror
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Tungsten appears to be a candidate for a neutrino factory solid target and should last for several years.
In this time it will receive ~10-20 dpa. This is similar to the 12 dpa suffered by the ISIS tungsten target with no problems.
Tantalum is too weak at high temperatures to withstand the stress waves.
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
A new idea for NuFact targets and beam dumps
Otto Caretta
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Work by Pugnat & Sievers
NuFact conceptual study for 1MW target
Tantalum packed bed (2mm particles) in flowing He
Already proposed by P. Sievers (CERN): packed bed targets
NuFact target
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
The new idea: a fluidised bed/jet
• A Fluidised jet of tungsten or tantalum particles in He could be used as a neutrino factory target– It could have high Z + high volume density– Can be effectively removed from the solenoid field hence
reducing the pion reabsorption– Can be replenished as particles wear out– Particles can be easily cooled (in an external fluidised bed)
A fluidised bed/jet of sand particlesof
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Fluidised pipe flow vs injection
High concentration homogeneous particulate flow is difficult to maintain
over long distances
However the solid phase can be effectively collected in a conveyor and injected at/near the point of use in high concentrations (5:1 to
90:1 solid/gas)
Very similar to the jet produced by a grit blasting
device: it is all standard technology!
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
A fluidised bed/jet:
• Has the same advantages as the packed bed:– a near hydrostatic stress field develops in the particles so higher
energies can be absorbed before material damage– The flowing fluid provides high heat transfer so the bed can cope with
higher energy densities and total power (and perhaps more than one beam pulse)
• Plus some more:– Can have very high Z and density – Can be shaped as required– Can be easily renewed/replenished as the particles wear or get
damaged– Will absorb only the designed amount of energy and then flow out of
the scene to get cooled and replenished (if necessary)– It carries both the advantages of the solid phase (high density) and of
the liquid phase (metamorphic, pumpable, replenishable)
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
Particle jet as a NuFact target
solenoid
Particles jet
He flow
beam
Pionshower
BENE/CARE Frascati 14-17 November 2006 CJ Densham CCLRC Rutherford Appleton Laboratory
BENE target work: the future
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