The Operating Theory of UVTron Flame Detector Sensor
1. when the cathode is exposed to ultraviolet light,
photoelectrons are emitted from the cathode and then
accelerated toward anode by the electric field.
2. when voltage applied, the electric field became stronger,the kinetic electrons startes to ionize the gas.

3. Because of the ionization, more electrons were generated. At the same time, postive ions accelerated and collide the cathode, generating secondary electrons.

This avalance process causes a large current between anode and cathode and discharge take place.

The UV Tron driving circuit board look for the discharge effect, and then provides one pulse outputs signal to the users.