tungsten powder test at hiradmat scientific motivation
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Tungsten Powder Test at HiRadMat Scientific Motivation P. Loveridge, T. Davenne, O. Caretta, C. Densham, J. O’Dell, N. Charitonidis 23 April 2011. Motivation. - PowerPoint PPT PresentationTRANSCRIPT
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Tungsten Powder Test at HiRadMatScientific Motivation
P. Loveridge, T. Davenne, O. Caretta, C. Densham, J. O’Dell, N. Charitonidis23 April 2011
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Motivation
• Designing targets for new accelerator based facilities is becoming more and more challenging due to increasing accelerator beam power and the associated power deposition in the target.
• Targets must sometimes accommodate significant power deposition in continuous form or sometimes as an intense pulse followed by an interval of cooling.
• Maintaining the target temperature and stress levels within safe limits is the main design driver and results in increasingly elaborate designs as time averaged and pulse power deposition are increased
Solid peripherally cooled targets Segmented Targets
Flowing or rotating Targets
Increasing Power Deposition
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~940 mm
Titanium target body
Graphite(ToyoTanso IG-43)
Helium cooling
Graphite to titanium diffusion bond
Ti-6Al-4V tube and windows
(0.3 mm thick)
Solid targetsT2K target designed for750kW beam
Prefer small diameter to conduct heat to surface
Limit of approximately 1MW for peripherally cooled solid targets
Dynamic Stress in T2K Graphite Target After a Single Beam Spill at 400°C, Tspill = 4.2 micro-second
3.3e14 protons @ 30 GeV, beam sigma = 4.24mm, target diameter = 26 mm
-10
-5
0
5
10
0 1 2 3 4 5
Time (milli-sec)
Stre
ss (M
Pa)
VM-Str @ Gauge pt. Rad-Str @ Gauge pt. Long-Str @ Gauge pt.
Prefer large beam sigma to reduce dynamic stress due to pulsed beam
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Segmented targets
ISISEuronu superbeamPacked bed Concept for 4MW beam
Increased surface area. Coolant reaching maximum energy deposition region. Reduced static and dynamic stresses.
Increased beam power possible with thinner plates
0
50
100
150
200
250
300
350
1.00E-09 1.00E-08 1.00E-07 1.00E-06 1.00E-05
Peak
Von
-Mise
s St
ress
[MPa
]
Energy deposition time [seconds]
peak stress
expansion time
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Gap of 2mm
Flowing and rotating targets
Continuously refresh target material to accommodate multi-MW power deposition
SNS mercury target
5MW ESS target wheel concept
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0
200
400
600
800
1000
1200
1 10 100 1000 10000
Peak
tem
pera
ture
jum
p [K
]
Time averaged power deposited [kW]
Mu2e (8GeV, 25kW, 588kHz, 100ns, 1mm)
T2K (30GeV, 750kW, 0.47Hz, 5μs, 4.24mm)
Numi (120GeV, 400kW, 0.53Hz, 8μs, 1mm)
Nova (120GeV, 700kW, 0.75Hz, 8μs, 1.3mm )
LBNE (120GeV, 2.3MW, 0.75Hz, 10μs, 1.5mm+)
ISIS (800MeV, 160kW, 50Hz, 200ns, 16.5mm)
EURONu (4.5GeV, 4MW, 50Hz, 5μs, 4mm)
Neutrino Factory (8GeV, 4MW, 50Hz, 2ns, 1.2mm)
ESS (2.5GeV, 5MW, 14Hz, 2.86ms)
ADSR
Limitations of target technologies
Peripherally cooled monolith
Flowing or rotating targets
Segmented
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Thermal Shock in liquid targets
Merit, Flowing mercury jet 14GeV proton beam Kirk et al.
Pulsed proton irradiation of mercury target. Cavitation of mecury causing damage to annealed stainless steel containment LANSCE-WNR Riemer et al.
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Is there a ‘missing link’ target technology?
Some potential advantages of a flowing powder:Resistant to shock waves
Quasi-liquid: can be conveyed in a pipeOffline cooling
Few moving partsMature technology
Areas of concern can be tested off-line
Open jets
SOLIDS LIQUIDS
Monolithic Flowing powder Contained liquidsSegmented
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Open jet:
Contained discontinuous dense phase:
Contained continuous dense phase:
Potential Multi-MW Powder Target Applications
Powder target integrated with magnetic horn for superbeam
Powder target integrated with solenoid for Neutrino factory
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Tungsten Powder Test Programme
• Plant at RAL developed to do offline testing
– Dense phase and lean phase transport
– Erosion studies– Heat transfer and cooling of powder
1
2
3
4
1. Suction / Lift2. Load Hopper3. Pressurise Hopper4. Powder Ejection and Observation
Low Velocity
High Velocity
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Motivation for in-beam powder test
• Splash and cavitation in a liquid (mercury) is a result of propagation and reflection of pressure waves through a continuous medium.
• It has been asserted that powder will not be subject to splashing or violent events because of its discrete nature. Individual powder grains do not easily transmit pressure waves to neighbouring grains and as such pressure waves tend to be contained within the grains.
• A mechanism for a powder eruption has been identified as a result of a beam induced pressure rise in the carrier gas. The expansion of the carrier gas may be violent enough to aerodynamically lift some powder. While this is a potentially interesting threshold to find we expect that it will confirm that eruption velocities are small compare to the splashing velocities observed with mercury.
• In order to confirm these assertions the response of a powder target to the proton beam must be tested to definitively answer the following two questions
• Will a powder target splash/erupt?• Can you propagate a pressure wave through a powder target to its container?
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Mercury Thimble In-beam test