Ignition SystemElectrical Sparkby Various (Unison Industries, Champion, engine manufacturers)
Typical Specifications
Voltage
10,000u201330,000 V
Spark Energy
1u201350 mJ per spark
Spark Rate
50u2013200 sparks/second
Operating Principle
A high-voltage electrical discharge across a gap creates a plasma arc that raises the local temperature of the propellant mixture above its auto-ignition point. The spark energy is typically 1–50 millijoules, delivered at 10,000–30,000 volts.
Spark igniters use an electrical discharge to directly ignite propellant mixtures in the combustion chamber or an auxiliary igniter chamber. They are among the simplest ignition systems and are commonly used in gas-generator cycle and expander-cycle engines. The spark provides the activation energy needed to initiate combustion of premixed or partially mixed propellants.
Materials
Used In Engines
Common Failure Modes
Electrode erosion, insulator cracking, fouling from combustion products, voltage leakage in humid conditions
Recent Innovations
Dual-redundant spark systems, semiconductor exciter units, surface-gap plugs for wet conditions
