US20120103302 shows a spark ignited prechamber combustion system typically used for IC engines. It basically consists of a chamber which has a input of premixed fuel-air mixture and a spark plug to start the fire. This device spews out hot gases and some amount of flame into the chamber. Not posting images due to copyrights issue
NASA Technical Memorandum 106493 Hydrogen-Oxygen Torch Ignitor shows one of NASA’s design for igniter. The main difference is that the design incorporates non-premixed fuel-oxidiser entry into the igniter combustion chamber.
The IC engine spark igniter appears to be more robust and functionally better than that available in NTRS as mixing does not occur close to ignition point.
But many sources on spark ignition system for rocket appears to follow the reference cited. What is the reason? In what way is the two system different? Is the choice for a simpler ignition system in rockets stem from mass point of view(ie to have a lighter igniter)?