Process is as follows.

Electric motor or air (depending on engine manuf.) spins the turbine shaft. Air enters combustion chamber and propane is injected. The glow plug ignites the propane. Now you have fire and exhaust.

The exhaust spins the "turbine wheel" which turns the compressor wheel, more air. Propane continues to run the process, the glow plug is off when some arbitrary temp is reached. more propane........

When you are up to temperature and RPM, the propane is turned off as kerosene or jet A has been injected via a fuel pump into the combustion chamber. It is atomized by little syringe type tubes.

The glow plug is not in the process during the actual running of the turbine.