Outstanding issues for a Mercury Beam Dump

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29 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Outstanding issues for a Mercury Beam Dump

Tristan Davenne

STFC Rutherford Appleton Laboratory, UK


UKNF meeting

Lancaster University

23
rd

April
-
2009


Mercury beam dump design from NUFACT Feasibility Study

Peter Loveridge, November
-
2008

Mercury beam dump design from NUFACT Feasibility Study


Fluka Simulation
-

Energy deposition in mercury pool 24 GeV beam

How much of the beam energy is absorbed in the beam dump?

Agitation ‘eruption’ of mercury pool surface due to 24GeV proton beam


Autodyne simulation

Splash following pulse of 20Terra protons




Autodyne simulation
-

Fluid Structure interaction

Damage to underside of 15mm stainless steel plate


Thermal shocks and
magnetohydrodynamics in
high

power mercury jet targets

J Lettry, A Fabich, S Gilardoni,
M Benedikt, M

Farhat and E Robert

Damage as a result of high speed impact of a mercury droplet

Stainless Steel vs. Ti
-
6Al
-
4V

Splash mitigation

Consider helium bubbles in beam dump to reduce splash velocity

helium

Proton
beam

Mercury beam dump design from NUFACT Feasibility Study

Agitation of mercury pool surface due to
impinging mercury jet

2 phase CFX model

mercury jet velocity = 20m/s

Angle = 5.7
°

mercury pool surface area = 0.05m
2

Conclusions

Simulations show that mercury splashes with a velocity of 75m/s will result when a
pulse from the undisrupted 24GeV beam is absorbed by the mercury beam dump.

(Mercury splash velocity of 30m/s has been observed experimentally when a 1GeV
proton beam interacted with a trough of mercury.
Lettry

et al.)


A 3mm diameter mercury droplet impacting a stainless steel plate at 75m/s is
predicted to cause significant damage. Ti
-
6%Al
-
4%V is predicted to be more
resistant to damage due to higher ultimate strength and shear strength.


Significant agitation of the mercury surface also results from the impingement of
the mercury jet.



11/29/2013

Outstanding Issues


1.
Is there space inside the solenoid to house a large enough mercury beam
dump?
(Must consider fluctuating mercury level as a result of mercury jet and
proton beam.)

2.
How much shielding required?
(Superconducting materials have very low heat
capacity so need to ensure beam energy is captured in the dump and
shielding.)

5.
What material should the inside surfaces of the beam dump and solenoids be
made of?
(Material selection critical in terms of resistance to pitting)

6.
Is an active mitigation device desirable to reduce the splash that results from
the proton beam interaction?
(sprung baffles, helium bubbles etc)


11/29/2013

Instantaneous Energy Deposition

Result of ‘instantaneous’ energy deposition

1.
Increase in temperature causes pressure rise


(analagous to Youngs Modulus linear
relationship between stress and strain)




2.

Strain energy is built up in the fluid due to
compression (area under graph)





Ref (Sievers & Pugnat)


3.

Strain energy will be released as kinetic
energy






4.

Expansion velocity is proportional to energy
deposition

T
K
P



0
20
40
60
80
100
120
140
0
0.0002
0.0004
0.0006
αΔT
pressure [bar]
Strain energy



e
unit volum
per

2
2
T
K
E





v
T
v
T
K







so

2
1
2
2
2
Sievers & Pugnat 2000 considered a

parabolic radial energy deposition in 2cm
diameter mercury target

and reported a

radial velocity at surface of mercury jet due to
proton beam is 36m/s

-

MERIT target



energy deposition from MARS

B = 15 T

Goran Skoro

Beam


67 mrad

Target


33 mrad

g

g

Autodyne Model of Merit Jet

beam energy = 24GeV

bunches in a pulse = 4

pulse duration = 2.3us

total energy deposition in mercury in a pulse = 8kJ

Autodyne Model of Merit Jet


Beam at 33mrads to 10mm diameter mercury jet

Autodyne Model of Merit Jet

Max radial Velocity 93m/s