Energy is stored in primary C

first half cycle (0 degrees)

spark gap breaks down

energy flows from primary C into primary L

some couples to secondary L (roughly 20%, assuming k=0.2)

half cycle peaks (90 degrees) (max current in L)

primary L energy flows back to primary C (the 80% remaining, less losses in spark gap)

secondary L energy flows to secondary C (partly self, partly top load), raising its voltage

Air breaks down next to secondary C (charge/current flows out from topload, limiting the voltage rise)

zero crossing (180 degrees) (max voltage on C)

voltage starts to drop on topload, charge stops flowing into spark, but hot gas remains

energy flows back into primary L from primary C

remaining energy (that didn't go into making the spark) in secondary C flows back into secondary L, some dissipated as heat in the windings

some additional energy is added to secondary L by coupling from primary L (20% of the 75-80%, or 16% of original Cpri energy)

second half cycle peaks (270 degrees) (max current in L)

primary L energy flows back to primary C

secondary L energy flows back to secondary C, raising its voltage, continuing the spark growth.

tcspark.htm 5 March 2001