# Presentation: 329901

## Simulation of Muon Collider Target Experiments 

- Simulation of Muon Collider Target Experiments

- Yarema Prykarpatskyy

- Center for Data Intensive Computing
- Brookhaven National Laboratory
- U.S. Department of Energy
- yarpry@bnl.gov

## Talk outline

- Numerical methods for the hyperbolic subsystem. The *FronTier  Code*
- Numerical simulation of the interaction of a free mercury jet with a proton pulse
- MHD simulations: stabilizing effect of the magnetic field
- Numerical simulation of the interaction of mercury with a  proton pulse in a thimble (BNL AGS and CERN ISOLDE experiments)
- Conclusions
- Remarks on the future research plans

## Numerical methods for the hyperbolic subsystem. 

- We used FronTier code with free interface support
- FronTier uses method of front tracking
- FronTier has large collection of Riemann solvers:
- 	MUSCLE (Monotonic Upstream Centered Difference Scheme for Conservation Laws)
- 		exact Riemann Solver
- 		Colella-Glaz approximate Riemann solver
- 		Gamma low fit
- 		Dukowicz Riemann solver
- For material modeling we use realistic models of the equation of state:
- 		polytropic EOS
- 		stiffened polytropic EOS
- 		two phase EOS for cavitating liquid
- 		SESAME EOS library

## Isentropic two phase EOS model for cavitating liquid

- Approach: connect thermodynamically consistently different models for different phases
- Pure liquid is described by the stiffened polytropic EOS model (SPEOS)
- Pure vapor is described by the polytropic EOS model (PEOS)
- An analytic model is used for the mixed phase
- SPEOS and PEOS reduced to an isentrope and connected by the model for liquid-vapor mixture
- All thermodynamic functions depend only on density

## The EOS 
does not take into account drag forces, viscous and surface tension forces
does not have full thermodynamics

- does not take into account drag forces, viscous and surface tension forces
- does not have full thermodynamics

## Applications: Muon Collider TargetNumerical simulation of the interaction of a free mercury jet with high energy proton pulses in a 20 T magnetic field

## Simulation of the Muon Collider target. The evolution of the mercury jet due to the proton energy deposition is shown.No magnetic field

**t = 0**

**t = 80**

## Jet in a uniform magnetic field

- Stiffened polytropic EOS was used to model the mercury jet
- A uniform magnetic field was applied to the mercury jet along the axis. The Lorentz force due to induced currents reduced both the shock wave speed in the liquid and the velocity of surface instabilities

## MHD simulations: stabilizing effect of the magnetic field.

**B = 0**
**B = 2T**
**B = 4T**
**B = 6T**
**B = 10T**

## Velocity of jet surface instabilities in the magnetic field

## Numerical simulation of the interaction of a free mercury jet with high energy proton pulses using two phase EOS

- Evolution of the mercury jet after the interaction with a proton pulse

## Mercury thimble experiment at AGS (BNL)

**Mercury thimble experiment at AGS (BNL)**
- Left: picture of the experimental device
- Right: schematic of the thimble in the steel bar

## Mercury splash (thimble): experimental data

- Mercury splash at t = 0.88, 1.25 and 7 ms after proton impact of 3.7 e12 protons

## Mercury splash (thimble): numerical simulation

## Mercury splash (thimble): numerical simulation

## Increasing the spot size of the proton beam results in a decrease of the splash velocities

## Conclusions: mercury jet simulations

-  The one-phase stiffened polytropic EOS for liquid led to much shorter time scale dynamics and did not reproduce experimental results at low energies.
-  The multiple reflections of shock/rarefaction waves from the jet surfaces and a series of Richtmyer-Meshkov  type instabilities on the jet surface were obtained using of the stiffened polytropic equation of state for a one phase fluid
-  Numerical experiments with the two phase EOS allowing a phase transition showed cavitation of the mercury due to strong rarefaction waves
-  Application of different equations of state for modeling mercury jet in the strong magnetic field confirms stabilizing effect

## Conclusions: mercury splash 

-  Numerical simulations show a good agreement with experimental data at early time.

-  The lack of full thermodynamics in the EOS leads to some disagreements with  experiments for the time evolution of the velocity during several microseconds. Can be corrected by the energy deposition.

-  Equation of states needs  additional physics (better mechanism of mass transfer, surface tension, viscosity etc.). Direct simulations and EOS based on the Rayleigh-Plesset equations will be used.

- Experimental data on the evolution of the explosion velocity (from Adrian Fabich’s thesis)