A corona igniter 20 includes a coil 24 with a plurality of copper windings 26 extending longitudinally along a coil center axis ac. A magnetic core 30 is disposed along the coil center axis ac between the windings 26 and includes a plurality of discrete sections 32. The discrete sections 32 are spaced axially from one another by a core gap 34 filled with a non-magnetic gap filler 78. The magnetic core 30 has a core length lm and the coil 24 has a coil length lc less than the core length lm. A coil former 62 having a former thickness tf spaces the coil 24 from the magnetic core 30. A length difference ld between the core length lm and the coil length lc is preferably equal to or greater than the former thickness tf.