1. Highlights Highlights of HEROS : First RT model to include spatial dependency of microstructure Ability to model Free-Surfaces implantation, and temperature Detailed discretization of spatial variables Includes detailed temperature driven Bubble kinetics. Models pulsed mode of damage, Models large temperature fluctuations, which are critical for He-bubble kinetic processes Automated spatial discretization NUMERICAL CALCULATION (HEROS) SCHEME He-Bubble Kinetics Included in HEROS + Drift + Coalescence + Surface Loss Reaction By Vol Diffusion: By Surf Diffusion: By Vol Diffusion: By Surf Diffusion: In first 0.1  m: T1T1 T 1 < T 2 T2T2 Temperature Distance Volume Diffusion Surface Diffusion Bubble Bubble Volume Diffusion Bubble Surface Diffusion Brownian Motion Directed Migration in Temp. Gradient Kinetic Rate Equation for Vac., SIA, He, HeV, He 2 V, He 2 Kinetic Rate Equation for Bubbles, PPT-B, GB-B, Loops etc. Spatial (x) Diffusion Term (1-D) Radiation Damage Implantation RATE THEORY MODELING Modeling of Implanted Helium in IFE First Wall Tungsten Armor Qiyang Hu, Shahram Sharafat, Nasr M. Ghoniem University of California Los Angeles, Los Angeles, CA. INTRODUCTION: High Average Power Laser Program Workshop, LLNL, June 20 th and 21 st, 2005 CONCLUSIONS  A comprehensive RT-based He-bubble evolution model has been developed.  HEROS includes: (1) Radiation damage, (2) He-Vacancy clusters, (3) Bubble Nucleation, (4) Bubble Resolution, (5) Bubble Evolution, (6) Diffusion and Drift of Bubbles to Free Surfaces.  The model predicts that under HAPL pulsed mode operation helium is recycled efficiently from the W-armor, because of:  High Simultaneous Self-Damage by Debris and Burn Ions  High Temperature rise (2200 o C) facilitating rapid diffusion. RESULTS  HAPL is developing a SOLID-Tungsten FW based IFE Reactor:  High Debris and Burn Ion implantation rates occur consisting of: P, D, T, He, C, Au, and Pt.  Helium poses the greatest challenge, because it can form bubbles which deteriorate thermo-mechanical properties of the W-armor.  The goal of this research is to model Helium behavior under pulsed IFE conditions.  This challenge requires the use of RATE THEORY because of the multiscale nature of the problem, which spans atomistic to um-size microstructural processes.  At UCLA we developed the HEROS code to model helium behavior under pulsed IFE conditions:  The HEROS code includes: oRadiation Damage oSpatial Bubble nucleation and growth oBubble Kinetics including loss at Free Surface oEvolving Microstructural features, such as dislocation network. Rate Theory Atomistic He-Relevant Migration Mechanisms included in HEROS 1.Migrating Interstitial Helium 2.Migrating Vacancy 3.Substitutional He  Interstitial He due to thermal dissociation 4.Helium jumping between Vacancies “riding along in different buses” 5.Substitutional He  Interstitial He due to SIA replacement 6.Collisional displacement of He (high damage rates) Schematic of He-diffusion relevant mechanisms w/o irradiation Bubble Nucleation Steps: Self-Damage induced plus “Thermal Vacancies” (C v e ) Interstitial He arrives He is trapped in Vacancy Bubble Nucleus forms (<nm) Bubbles pressurized by He Vacancies form READILY on bubble surface Bubble stabilized by SIA emission CveCve Distance x SIA is expelled from surface leaving behind a vacancy Helium-Bubble Nucleation of HEROS Duration Time: 0.8~2.1  s Duration Time: 0~0.8  s HEROS Input Profiles Duration Time: 0.8~2.1  s Use SRIM calculations to establish Debris Ion Implantation Profiles: Includes the simultaneous SELF-DAMAGE Of all Debris Ions: P, D, T, He, C, Au, & Pt T=10 -10 secT=10 -8 sec T=1.5  sec T=0.4  secT=0.7  sec T=2.1  secT=0.8  sec T=0.8msec T=0.2sec End of Implantation High Temperature Annealing Debris Burn End of Pulse One Beginning of Pulse Two End of Implantation in Pulse Two End of Pulse Two T=0.2s+0.7  sT=0.2s +2.1  s T=0.4sec Spatial Bubble Evolution Showing Effects of Simultaneous Self-Damage of Debris and Burn Ions: P, D, T, He, C, Au and Pt Average He-Bubble Radius He-Bubble Concentrations Debris Ion Produced Self- Inerstitial W-atom (PKA) Collision Cascade (SIA) Helium Bubble Smaller Helium Bubble decorated with He-Vacancy Clusters Schematic of He-Bubble Resolution Self-Damage Rate Profiles (SRIM) mm cm