Welcome to the new GE PowerPoint template!

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 costumers 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
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