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 Review GA, San Diego April 4-5, 2002 April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 1
Source Chamber Physics Modeling Chamber Region Wall Region Energy input Mass input Momentum input Driver beams Transport + deposition Pressure (T) Energy Equations Condensation Radiation transport Momentum Conservation Equations Pressure (density) Viscous dissipation Mass Conservation Equations (multi-phase, multi-species) Condensation Aerosol formation Evacuation Phase change Energy deposition Condensation Convection Pressure (T) Impulse Wall momentum transfer (impulse) Evaporation, Sputtering, Other mass transfer Condensation Conduction Thermal capacity Thermal stress Thermal shock Stress/strain analysis Fluid wall momentum equations April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 2
Chamber Dynamics and Clearing 2001 Statement of Work (I) 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. Single species code with rectangular domain completed using progressive approach - 1-D --> 2-D - inviscid --> viscous (to be presented by Z. Dragojlovic) Scoping studies to assess importance of different phenomena for inclusion in the code. Develop simple modules defining the physics of the different phenomena. 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 3
Chamber Dynamics and Clearing 2001 Statement of Work (II) 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. 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 Scope the range of chamber dynamics and clearing experiments that can be carried out in a facility producing 100-1000 J of X-ray. (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 4
Wall Interaction Module Has Been Developed 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 Example IFE Chamber Wall Configuration Under Energy Deposition q''(subl./evap.) Photons Melt Layer q''(cond.) Re- radiation q'''(from photons and ions) To be linked to gas dynamic code April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 5
Other Erosion Processes to be Added (ANL) Scoping analysis performed - Vaporization, physical sputtering, chemical sputtering, radiation enhanced sublimation 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 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) Tungsten April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 6
Models Provided for RES, Chemical Sputtering and Physical Sputtering (ANL) 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 April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 7
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 8
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 Energy deposition (J/m 3 ) Energy Deposition as a Function of Penetration Depth for 154 MJ NRL DD Target 1x10 11 1x10 10 1x10 9 1x10 8 1x10 7 Debris ions, C Fast ions, W Photons, W Photons, C Debris ions,w 1x10 6 1x10-8 1x10-7 1x10-6 1x10-5 1x10-4 1x10-3 1x10-2 Penetration depth (m) C density = 2000 kg/m 3 W density = 19,350 kg/m 3 Fast ions, C Energy deposition (J/m 3 ) Energy Deposition as a Function of Penetration Depth for 401 MJ NRL DD Target 1x10 12 1x10 11 1x10 10 1x10 9 1x10 8 Debris ions,w Debris ions, C Fast ions, W Photons, W Photons, C Fast ions, C 1x10 7 1x10-8 1x10-7 1x10-6 1x10-5 1x10-4 1x10-3 1x10-2 Penetration depth (m) C density = 2000 kg/m 3 W density = 19,350 kg/m 3 April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 9
Spatial and Temporal Heat Generation Profiles in C and W for 154MJ Direct Drive Target Spectra 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 10
Temperature History of C and W Armor Subject to 154MJ Direct Drive Target Spectra with No Protective Gas Temperature ( C) 3000 2600 2200 1800 1400 1000 600 3-mm Tungsten slab Density = 19350 kg/m 3 Coolant Temp. = 500 C h =10 kw/m 2 -K 154 MJ DD Target Spectra Surface 1 micron 5 microns 10 microns 100 microns Temperature ( C) 1800 1600 1400 1200 1000 800 3-mm Tungsten slab Density = 19350 kg/m 3 Coolant Temp. = 500 C h =10 kw/m 2 -K 154 MJ DD Target Spectra Photon energy dep. only Surface 1 micron 5 microns 10 microns 100 microns 200 0.0x10 0 1.0x10-6 2.0x10-6 3.0x10-6 4.0x10-6 5.0x10-6 6.0x10-6 7.0x10-6 8.0x10-6 9.0x10-6 1.0x10-5 600 2000 1800 Time (s) Surface 1 micron 400 1.0x10-12 1.0x10-11 1.0x10-10 1.0x10-9 1.0x10-8 1.0x10-7 1.0x10-6 Time (s) Temperature ( C) 1600 1400 1200 1000 800 600 3-mm Carbon Slab Density= 2000 kg/m 3 Coolant Temperature = 500 C h =10 kw/m 2 -K 154 MJ DD Target Spectra Sublimation Loss = 9x10-18 m 5 microns 10 microns 100 microns Initial photon temperature peak is dependent on photon spread time (sub-ns from J. Perkins and J. Latkowski) 400 0.0x10 0 1.0x10-6 2.0x10-6 3.0x10-6 4.0x10-6 5.0x10-6 6.0x10-6 7.0x10-6 8.0x10-6 9.0x10-6 1.0x10-5 Time (s) April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 11
Document and release stage 1 code Exercise stage1 code: Future Effort (1) - 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 12
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 April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 13