Extinction, ignition

• What two quantities are balanced at the point of flame extinction or ignition?
• What is the extinction hole (or channel) width proportional to in terms of premixed flame quantities?
• What was the $b$ parameter used for in the analysis?
• For flame extinction, we consided round holes, or slot channels. What geometry is typically assumed for ignition?
  • What other shape might make sense when considering spark ignition?
• How would you compute $\alpha$ when evaluating a critical radius?