April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 1 Chamber Dynamics and Clearing Code Development Effort A. R. Raffray, F. Najmabadi,

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

1

Chamber Dynamics and Clearing Code Development Effort

A. R. Raffray, F. Najmabadi, Z. Dragojlovic

University of California, San Diego

A. Hassanein

Argonne National Laboratory

P. Sharpe

INEEL

HAPL ReviewGA, San Diego

April 4-5, 2002

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Chamber Physics ModelingChamber RegionSource Wall Region

Driver beams

Momentum input

Momentum Conservation Equations

Wall momentum transfer(impulse)

Fluid wall momentum

equations

Energy Equations Phase change

Condensation

Conduction

Energy input

Thermal capacity

Radiation transport

Transport + deposition

Condensation

Pressure (T)

Impulse

Pressure (T)

Pressure (density)

Viscous dissipation

Mass input

Mass Conservation Equations (multi-phase, multi-species)

Evaporation,Sputtering,Other mass transfer

Condensation

Evacuation

Energy deposition

Convection

Thermal stress

Stress/strain analysis

Condensation Aerosol formation

Thermal shock

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Statements of work:

• Initiate development of a fully integrated computer code to model and study the chamber dynamic behavior.

• Deliver the core of the code including the input/output interfaces, the geometry definition and the numerical solution control for multi-species (multi-fluid), 2-D transient compressible Navier Stokes equations.

• Scoping studies to assess importance of different phenomena for inclusion in the code.

• Develop simple modules defining the physics of the different phenomena.

Chamber Dynamics and Clearing 2001 Statement of Work (I)

• Single species code with rectangular domain completed using progressive approach

- 1-D --> 2-D- inviscid --> viscous

(to be presented by Z. Dragojlovic)

• Results presented at last meeting for poor effectiveness of conduction, convection and radiation to cool protective gas

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Statements of work:

• Provide modules for chamber wall interaction modules which will include physics of melting; evaporation and sublimation; sputtering; macroscopic erosion; and condensation and redeposition.

• Scope the range of chamber dynamics and clearing experiments that can be carried out in a facility producing 100-1000 J of X-ray.

Chamber Dynamics and Clearing 2001 Statement of Work (II)

Wall interaction module developed as 1-D transient thermal model with ion and photon energy deposition, including melting and sublimation effect

Scoping analyses performed to decide on relative importance of other erosion mechanisms (ANL)

Sputtering and RES modeling equations provided by ANL, to be coded at UCSD

(to be presented by R. Raffray)

Completed

(to be presented by F. Najmabadi)

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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• Ion and photon energy deposition calculations based on spectra

- Photon attenuation based on total photon attenuation coefficient in material

- Use of SRIM tabulated data for ion stopping power as a function of energy

• Transient Thermal Model

- 1-D geometry with temperature-dependent properties

- Melting included by step increase in enthalpy at MP

- Evaporation included based on equilibrium data as a function of surface temperature and corresponding

vapor pressure- For C, sublimation based on latest recommendation from

Philipps

• Model calibrated and example cases run

• To be linked to gas dynamic code

Wall Interaction Module Has Been Developed

Example IFE Chamber Wall Configuration UnderEnergy Deposition

Photons

Melt Layer

Re- radiation

q'''(from photons and ions)

q''(subl./evap.)

q''(cond.)

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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• Scoping analysis performed - Vaporization, physical sputtering, chemical sputtering, radiation enhanced sublimation

Other Erosion Processes to be Added (ANL)

• These results indicate need to include RES and chemical sputtering for C (both increase with

temperature)

• Physical sputtering relatively less important for both C and W for minimally attenuated ions

(does not vary with temperature and peaks at ion energies of ~ 1keV)

Plots illustrating relative importance of erosion mechanisms for C and W for 154 MJ NRL DD target spectra

Chamber radius = 6.5 m.

CFC-2002U

Tungsten

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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• Recommended models (equations) provided for inclusion in wall interaction module for physical and chemical sputtering and

radiation enhanced sublimation - Model based on analytical and semi-empirical approach

• Calibration runs will be done

• Further effort required for macroscopic erosion- Scoping analysis

- Model development

Models Provided for RES, Chemical Sputtering and Physical Sputtering (ANL)

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Comparison Runs for Energy Deposition and Thermal Analysis (UCSD, UW and ANL)

• Prior results did not match very well

• We decided to:- Compare input data and resolve any differences- Run a few example cases for energy deposition and temperature

calculations

• Stopping power and energy deposition quite consistent now

• Very useful exercise

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Spatial Profile of Volumetric Energy Deposition in C and W for Direct Drive Target Spectra

• Tabulated data from SRIM for ion stopping power used as input

1x107

1x108

1x109

1x1010

1x1011

1x1012

1x10-8 1x10-7 1x10-6 1x10-5 1x10-4 1x10-3 1x10-2

Debris ions,W

Fast ions, C

Photons, W

Photons, C

Fast ions, W

Penetration depth (m)

Energy Deposition as a Function of PenetrationDepth for 401 MJ NRL DD Target

Debris ions, C

C density = 2000 kg/m3

W density = 19,350 kg/m3

1x106

1x107

1x108

1x109

1x1010

1x1011

1x10-8 1x10-7 1x10-6 1x10-5 1x10-4 1x10-3 1x10-2

Debris ions,W

Fast ions, C

Photons, W

Photons, C

Fast ions, W

Penetration depth (m)

Energy Deposition as a Function of PenetrationDepth for 154 MJ NRL DD Target

Debris ions, CC density = 2000 kg/m3

W density = 19,350 kg/m3

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Spatial and Temporal Heat Generation Profiles in C and W for 154MJ Direct Drive Target Spectra

0.0x100

1.0x1016

2.0x1016

3.0x1016

4.0x1016

5.0x1016

Temporal and Spatial Profile of Ion Power Deposition inC Armor from 154 MJ DD Target Spectrum

0.0x100

1.0x1016

2.0x1016

3.0x1016

4.0x1016

5.0x1016

Temporal and Spatial Profile of Ion Power Deposition inW Armor from 154 MJ DD Target Spectrum

• Assumption of estimating time from center of chamber at t = 0 is reasonable based on discussion with J. Perkins and J. Latkowski

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Temperature History of C and W Armor Subject to 154MJ Direct Drive Target Spectra with No Protective Gas

• Initial photon temperature peak is dependent on photon spread time (sub-ns from J. Perkins and J. Latkowski)

400

600

800

1000

1200

1400

1600

1800

1.0x10-12 1.0x10-11 1.0x10-10 1.0x10-9 1.0x10-8 1.0x10-7 1.0x10-6

Surface

1 micron

5 microns

10 microns

100 microns3-mm Tungsten slab

Density = 19350 kg/m3

Coolant Temp. = 500°C

h =10 kW/m2-K154 MJ DD Target SpectraPhoton energy dep. only

Time (s)

200

600

1000

1400

1800

2200

2600

3000

Surface

1 micron

5 microns

10 microns

100 microns

Time (s)

3-mm Tungsten slab

Density = 19350 kg/m3

Coolant Temp. = 500°C

h =10 kW/m2-K154 MJ DD Target Spectra

400

600

800

1000

1200

1400

1600

1800

2000Surface

1 micron

5 microns

10 microns

100 microns

Time (s)

3-mm Carbon Slab

Density= 2000 kg/m3

Coolant Temperature = 500°C

h =10 kW/m2-K154 MJ DD Target Spectra

Sublimation Loss = 9x10-18 m

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Future Effort (1)

• Document and release stage 1 code

• Exercise stage1 code:

- Investigate effectiveness of convection for cooling the chamber gas

- Assess effect of penetrations on the chamber gas behavior including interaction with mirrors

- Investigate armor mass transfer from one part of the chamber to another including to mirror

- Assess different buffer gas instead of Xe

- Assess chamber clearing (exhaust) to identify range of desirable base pressures

- Assess experimental tests that can be performed in simulation experiments

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development

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Future Effort (2)

• Implement development of stage 2 code - Extend the capability of the code (full inclusion of multi-species capability)

- Implement adaptive mesh routines for cases with high transient gradients and start implementation if necessary

- Work with INEEL to implement aerosol formation and transport models in the stage 2 code- Low probability for aerosol formation for dry wall concepts- However, major effect on target and driver even with minimal formation- Possible background plasma effect to slow down and stop ions (behavior of these

particles)

- Work with ANL to implement more sophisticated wall interaction models in stage 2 code

- Brittle destruction of carbon-based material- Droplets formation and splashing for metallic walls

• Develop a 0-D multi-species model to assess the range of species (neutral and plasma) that should be taken into accounts (S. Krasheninnikov)- If plasma effects are shown to be important, implement model in chamber

dynamics code