Progress Report on SPARTAN Simulation of IFE Chamber Dynamics

Farrokh Najmabadi and Zoran Dragojlovic

HAPL Meeting

March 3-4, 2005Naval Research LaboratoryWashington DC

Electronic copy: http://aries.ucsd.edu/najmabadi/TALKSUCSD IFE Web Site: http://aries.ucsd.edu/IFE

Thermo-Mechanical Response of Chamber Wall Can Be Explored in Simulation Facilities

SPARTAN features: Physics: Navier-Stokes equations with state dependent transport properties;

Coronal model for radiation. Numerics: Godunov solver; Embedded boundary; and Adaptive Mesh Refinement Two-Dimensional: Cartesian and cylindrical symmetry Use results from rad-hydro codes (BUCKY) as initial condition.

SPARTAN features: Physics: Navier-Stokes equations with state dependent transport properties;

Coronal model for radiation. Numerics: Godunov solver; Embedded boundary; and Adaptive Mesh Refinement Two-Dimensional: Cartesian and cylindrical symmetry Use results from rad-hydro codes (BUCKY) as initial condition.

All previous results were based on a Bucky run provided by Don Haines

All previous results were based on a Bucky run provided by Don Haines

A variety of chamber geometries has been considered

Infinite cylinder (Cartesian symmetry)

Infinite cylinder (Cartesian symmetry)

Finite cylinder (Cylindrical symmetry)

Finite cylinder (Cylindrical symmetry)

Sphere (Cylindrical symmetry)

Sphere (Cylindrical symmetry)

Octagon(Cylindrical symmetry)

Octagon(Cylindrical symmetry)

Without Radiation, a high temperature zone would be developed in the chamber

t = 0.5 ms

Tmax = 5.3 104 K Tmax = 3.1 105 K Tmax = 2.2 105 K

t = 3 ms(After one bounce)

t = 8 ms

Tmax = 1.3 105 K Tmax = 5.1 104 K Tmax = 3.2 104 K

t = 20 ms t = 100 mst = 65 ms

Convergence of shocksleads to a hot zone.

Convergence of shocksleads to a hot zone.

Hot zone does notdisappear

Hot zone does notdisappear

Without Radiation, a high temperature zone would be developed in the chamber

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100

time [ms]

En

ergy

[10

5 J]

Case I: No Radiation

Internal Energy

Kinetic Energy Conducted to wall

After the first “bounce” kinetic energyof gas is converted into internal energy(hot zone). Conduction to the wall is too slow.

After the first “bounce” kinetic energyof gas is converted into internal energy(hot zone). Conduction to the wall is too slow.

Case II: With Radiation

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100

time [ms]

En

ergy

[10

5 J]

The energy is dissipated by radiation. The gas temperatureis effectively pinned byradiation (~5,000K for Xe)

The energy is dissipated by radiation. The gas temperatureis effectively pinned byradiation (~5,000K for Xe)

Internal Energy

No Radiation

Radiation

Dynamic Evolution of Xe-filled Chambers

A large number of cases with different geometries were simulated: 3-D effects can be observed and sufficiently described by using a

combination of Cartesian and axisymmetric cylindrical 2-D models. Shape of the chamber makes little difference in peaks and averages of

the temperature (< 10%). Peak Xe temperature is set by radiation at about 5,000K. A Journal article was written but is currently shelved. (see below)

A large number of cases with different geometries were simulated: 3-D effects can be observed and sufficiently described by using a

combination of Cartesian and axisymmetric cylindrical 2-D models. Shape of the chamber makes little difference in peaks and averages of

the temperature (< 10%). Peak Xe temperature is set by radiation at about 5,000K. A Journal article was written but is currently shelved. (see below)

Status of Plans from Previous HAPL Meeting

Separate radiation step from the fluid dynamics in order to shorten the run time with the full radiation source term. Done! (only a factor of ~2 reduction in run time). We purchased a two-processor 64-bit (native) computer with fast

memory access: Drastic reduction in run time. Developed MATLAB based GUI for post-processing of the data. Developed a program to construct the problem geometry from

simple geometrical shape.

Separate radiation step from the fluid dynamics in order to shorten the run time with the full radiation source term. Done! (only a factor of ~2 reduction in run time). We purchased a two-processor 64-bit (native) computer with fast

memory access: Drastic reduction in run time. Developed MATLAB based GUI for post-processing of the data. Developed a program to construct the problem geometry from

simple geometrical shape.

Parametric study of different gases (Xe, He, D, T) and initial pressures in the chamber: We received Bucky runs for chambers filled with D, T, and Xe at

10, 30, and 50 mTorr. There are significant differences between new Bucky runs and one

received from Don Haines.

Parametric study of different gases (Xe, He, D, T) and initial pressures in the chamber: We received Bucky runs for chambers filled with D, T, and Xe at

10, 30, and 50 mTorr. There are significant differences between new Bucky runs and one

received from Don Haines.

Differences between Old and New Bucky Runs (50 mTorr Xe)

0.0E+00

2.0E-07

4.0E-07

6.0E-07

8.0E-07

1.0E-06

1.2E-06

1.4E-06

1.6E-06

1.8E-06

2.0E-06

0 200 400 600 800

radius [cm]

rho

[g/c

m3

]

rho @ 5.4 E-6 srho at 500 E-6 s

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0 100 200 300 400 500 600 700

radius [cm]

V [c

m/s

]

V @ 5.4 E-6 sV @ 500 E-6 s

Data from Don Haynes, 2001 Data from Greg Moses, 2004

Density

Velocity

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0 100 200 300 400 500 600 700

radius [cm]

V [c

m/s

]

V @ 1 E-6 sV @ 10 E-6 sV @ 100 E-6 sV @ 500 E-6 s

0.0E+00

2.0E-07

4.0E-07

6.0E-07

8.0E-07

1.0E-06

1.2E-06

1.4E-06

1.6E-06

1.8E-06

2.0E-06

0 200 400 600 800

radius [cm]

rho

[g/c

m3

]

rho @ 1 E-6 srho @ 10 E-6 srho @ 100 E-6 srho @ 500 E-6 s

Differences between Old and New Bucky Runs (50 mTorr Xe)

0.0E+00

5.0E+00

1.0E+01

1.5E+01

2.0E+01

2.5E+01

3.0E+01

3.5E+01

0 100 200 300 400 500 600 700

radius [cm]

T [e

V]

T @ 5.4 E-6 sT @ 500 E-6 s

0.0E+00

5.0E+00

1.0E+01

1.5E+01

2.0E+01

2.5E+01

3.0E+01

3.5E+01

0 100 200 300 400 500 600 700

radius [cm]T

[eV

]

T @ 1 E-6 sT @ 10 E-6 sT @ 100 E-6 sT @ 500 E-6 s

Temperature

Data from Don Haynes, 2001 Data from Greg Moses, 2004

Comparison of SPARTAN runs using Old and New Bucky Runs as initial conditions

Temperature

Data from Don Haynes, 2001 Data from Greg Moses, 2004

Tmax = 5,370 KTmin = Twall = 973 KTave = 3,640 K

Tmax = 4,690 KTmin = Twall = 973 KTave = 3,510 K

max = 1.2 g/m3

min = 0.3 g/m3

ave = 0.4 g/m3

max = 2.9 g/m3

min = 0.5 g/m3

ave = 0.7 g/m3

Density

30m Torr D Initial Condition from Bucky

Temperature increaseswith time.

Temperature increaseswith time.

Final Words…

Regime of validity of SPARTAN: Ku = /L < 0.01 Valid Ku ~ 1 Molecular flow, not valid 0.01 < Ku < ~ 0.2 Transition (transport coefficients should be

modified) but in IFE chambers transport is dominated by radiation

50 mTorr: D = 2 cm Xe = 1 cm OK 5 mTorr: D = 20 cm Xe = 10 cm Transition

(probably OK) 0.5 mTorr: D = 2 m Xe = 1 m Molecular flow (NO)

Regime of validity of SPARTAN: Ku = /L < 0.01 Valid Ku ~ 1 Molecular flow, not valid 0.01 < Ku < ~ 0.2 Transition (transport coefficients should be

modified) but in IFE chambers transport is dominated by radiation

50 mTorr: D = 2 cm Xe = 1 cm OK 5 mTorr: D = 20 cm Xe = 10 cm Transition

(probably OK) 0.5 mTorr: D = 2 m Xe = 1 m Molecular flow (NO)

Parametric study of different gases (Xe, He, D, T) and initial pressures in the chamber: Whenever Bucky initial conditions becomes available.

Parametric study of different gases (Xe, He, D, T) and initial pressures in the chamber: Whenever Bucky initial conditions becomes available.