Low pressure sodium lamp principle
- Aug 15, 2018 -

An electric light source that produces visible light by discharge using low pressure sodium vapor (working vapor pressure not exceeding a few kPa). The low pressure sodium lamp was invented in 1930. 1932

In the year, Philips, the Netherlands, commercialized low-pressure sodium lamps for the first time. After continuous improvement, the luminous efficiency of the low-pressure sodium lamp has reached 450 lm / W, becoming the light source with the highest luminous efficiency among various electric light sources. Low-pressure sodium lamp principle: It is an electric light source that emits light based on the principle of low-pressure sodium--rare gas discharge. Since sodium is a solid at room temperature, a gas discharge lamp using sodium alone is not easily activated. When the glass tube of the lamp is filled with a argon-helium mixture gas, that is, Penning gas, the lamp first exhibits a characteristic red light of krypton, and heat is generated to increase the temperature of the discharge tube, causing the sodium to begin to evaporate; due to the ionization potential and excitation potential of sodium It is lower than helium and argon, and the discharge is quickly transferred to the sodium vapor to emit visible light. The low-pressure sodium discharge radiation is concentrated on two double-D lines of 589.0 nm and 589.6 nm, which are very close to the highest value of the spectral light curve (555 nm), so the luminous efficiency is extremely high.