A Low-pressure sodium (LPS) lamp, also known as a Sodium oxide (SOX) lamp, is a type of lighting fixture which operates by passing an electric current through a mixture of sodium vapor and a noble gas, such as neon or argon, at low pressures and temperatures. LPS lamps are characterized by their unique yellow-orange light output, which is primarily emitted at a wavelength of 589.3 nanometers. This monochromatic light is highly efficient and has a high luminous efficacy, meaning that it produces a significant amount of visible light per unit of electrical power consumed.