Ignition SystemChemical (Pyrophoric)by SpaceX (implementation), various chemical suppliers
Typical Specifications
Ignition Delay
<50 ms
Fluid Per Start
~0.5u20131.0 kg (estimated)
Restarts Available
3u20134 per mission (Falcon 9)
Operating Principle
A measured quantity of TEA-TEB mixture is injected into the combustion chamber via a dedicated fluid circuit. On contact with the oxygen-rich environment, it spontaneously ignites, creating a flame kernel that ignites the incoming main propellants.
The TEA-TEB (triethylaluminum-triethylborane) ignition system uses a pyrophoric fluid mixture that spontaneously ignites on contact with oxygen. A small slug of TEA-TEB is injected into the combustion chamber just before the main propellants, providing a reliable ignition source. SpaceX uses TEA-TEB in Merlin engines, with enough fluid stored for multiple restarts during landing.
Materials
Used In Engines
Common Failure Modes
Fluid supply depletion (limits restarts), valve failure, line blockage, premature fluid decomposition
Recent Innovations
Metered slug injection for multiple restarts, integration with pintle injector, reliable ignition in vacuum conditions
