Trigger Coil Transformer
Trigger coil Transformers are used to provide a single, high-voltage pulse (in the order of several Kilo-Volts) to the flash tube's envelope.
The high voltage pulse is necessary for the Xenon gas to ionize, causing it to become highly conductive.
This process finally allows the lower voltage (several hundred Volts) storage capacitor to dump the energy into the flash tube's ionized gas, via the Anode and Cathode of the lamp.
Being High-voltage Pulsed transformers, they are used many times for CDI systems, Gas stove ignition, Electrical stimulation etc.