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 Review GA, San Diego April 4-5, 2002

A. R. Raffray, et al., Chamber Clearing Code Development 2 Chamber Physics Modeling Chamber Region Source 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 3 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 4 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 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 5 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

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 6 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 7 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 8 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 9 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

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 10 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 11 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)

April 4-5, 2002 A. R. Raffray, et al., Chamber Clearing Code Development 12 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 13 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