(A by far not complete selection of) Fundamental data & processes

1. (A by far not complete selection of) Fundamental data & processes related to the materials in light sources (what manufacturers need) Zoltán Tóth GE Consumer & Industrial, Budapest

2. Manufacturers aims • Costumer wants better ‘illumination • Initial Light output & Efficacy • Maintenance during lamp life • - Light output • - spectral distribution/color spread • - Efficacy • Optimized/better Light quality • - color/white light/reaction time/safety • - color research/McAdam ellipses • - new applications: medical, food quality, training, dimming studies,… • - novel light source families: exotic discharges, LEDs,… Better fulfil of costumer’s needs

3. Manufacturers constraints • price • - new materials & processes • Cost of light • lifetime, Reliability • RoHS, WEEE Material Science: properties and novel materials

4. High Intensity Discharge (HID) Technology Key science and technology areas : • Plasma physics : discharge models& diagnostics • see this workshop • radiative processes • electrode-plasma coupling • Discharge Chemistry, Thermochemistry • Materials • electrodes • ceramics • ceramic-metal interfaces • Lamp/Ballast Interaction • Processes and Equipment Material Science: properties and novel materials

5. Electrode system • Electron emission properties • work function • thoriated system: RoHS concern? • composition & chemistry on the surface • electrode-plasma interaction • diffusion processes inside the electrode • WFS: • Mapping (lateral resolution of ~5m) • Time dependent changes during heat treatment and/or gas exposure • But • geometrical effect (positioning) • polished surface or correction • effect of ion bombardment • connection to operating condition • beside lighting: welding electrodes

6. Electron emission properties • work function • thoriated system • composition & chemistry on the surface • electrode-plasma interaction • diffusion processes inside the electrode • electrical parameter stability • starting processes • sputtering, evaporation • deposits on the wall Electrode system • Starting • sputtering • kinetic : do we have enough energy ? • electronic : do we have this in oxides ? (energy level of electrode/e-mix, photons) • effect of the discharge atmosphere (dose, fill pressure) • effect of the electrode material (dopants, crystal structure) • effect of the e-mix material (if applied) • connected diagnostic tools : glow, glow to arc transition, temperature and charge distribution • Steady state operation : evaporation or desorption of the adatoms

7. Ceramics • Light Scattering • pores (inter- and intra granular) • dopants (MgO, Y2O3, ZrO2,…) • grain boundaries • hexagonal : birefringence • large grain size reduces strength • saphire • Chochralski • solid state conversion • cubic lattice crystals • sub-micron grain size • surface • polishing • Transparent ceramics for better optics • beside lighting: bullet proof window

8. Tangent (Z) Radial (X) Glass-metal and ceramics-metal interfaces Stresses • thermal expansion properties • modulus of elasticity • tensile strength • Poisson ratio • Critical Apparent Fracture Toughness • Stress behaviour at phase interface and at voids • summing rules for FEM studies • what is the optimal seal structure

9. Glass-metal and ceramics-metal interfaces: corrosion Arc tube Molybdenum foil Pinch • Reactive Metal halide salts: corrosion of molybdenum feedtrough foils • NaI reacts with molybdenum and forms Na2MoO4 • InI does not react with molybdenum, but diffuses into the deeper layers • Ceramics corrosion • composition and vapour pressure of the complexes • reaction of complexes with wall materials