November 8-9, Considerations for Small Chambers A. René Raffray UCSD With contributions from M. Sawan (UW), I. Sviatoslavsky (UW) and X. Wang (UCSD) HAPL Meeting University of Rochester's Laboratory for Laser Energetics Rochester, NY November 8-9, 2005

2 Considerations on Chamber Development for Materials Testing with Lower Energy Targets Lower yield targets (e.g ~30 MJ) -Smaller chambers -Revisit armor under reduced threat spectra If space to be used for materials testing, reduced breeding blanket coverage needs to be compensated to provide required tritium -Optimize blanket for breeding (Be as neutron multiplier, 6 Li enrichment, structure minimization) -Flexibility of adjusting breeding for different phases of testing (e.g. changing 6 Li enrichment) -No need for power production If testing regions are closer to micro-explosion and under more intense threat spectra, key issue is how to protect them and make sure no undesirable impurities enter chamber and affect its operation (e.g. target injection and survival, laser propagation)

November 8-9, Temperature History of W for Example Case with 30 MJ Yield and 5.5 m Chamber 1-mm W on 3.5 mm FS at 500 °C Peak temperature reduced to ~1200°C Probably lower than roughening threshold However, He retention is a concern at lower peak temperature.

November 8-9, Would Reduced Threat Spectra Allow for Possibility of Other Armor, e.g. SiC? SiC Properties: -Density = 3200 kg/m -Irradiation effects substantially reduce the conductivity: k irrad /k unirrad ~ 0.5 at ~ 1000°C

November 8-9, Chamber with SiC Armor He retention might be less severe than for W but would require high operating temperature (from initial literature survey, but needs further investigation) Can be bonded to FS Degradation of properties under irradiation a concern Erosion due to sputtering and other processes could lead to T co- deposition in cold regions

November 8-9, Summary Investigation of possibility of performing material testing with a lower gain target in a smaller chamber would include: -Testing requirements and impact on machine -Armor study and development (evaluate W based on latest info from our experiments, and look at other possibilities, e.g. SiC) - Chamber wall -Test regions closer to micro-explosion (challenging) -Blanket development -Impact of testing requirements must be included (loss of breeding coverage but also material choices, e.g. is water required for component testing or support? Is it acceptable if we choose a Li blanket?) - Maximize and provide flexibility of adjusting breeding (not enough tritium is a concern but too much tritium is also a concern!) -No need for power production