When the external power supply circuit is connected, the output end of the transformer will produce thousands of volts or even tens of thousands of volts of high pressure. When this high pressure is added to the electrodes at both ends of the neon tube, the charged particles in the neon tube are accelerated in the high-voltage electric field and fly toward the electrode, which can excite the production of a large number of electrons. These excited electrons are accelerated in high-voltage electric fields and collide with the gas atoms in the lamp. When the energy of these electrons colliding with free gas atoms is large enough, the gas atoms can be ionized to become positive ions and electrons, which is the ionization phenomenon of the gas.
The collision between the charged particle and the gas atom, the excess energy is emitted in the form of photons, which completes the whole process of the luminous light of the neon light.