A single-component calcium halophosphate Phosphor and a low pressure discharge lamp utilizing such a phosphor is provided having a lamp envelope having an inner surface, means within the lamp envelope for generating ultraviolet radiation; and a layer of a luminescent material adjacent the inner surface of the lamp envelope for generating visible light when impinged by the ultraviolet radiation. The inhibition layer is formed by coating the surface of the recording photoconductive layer with organic polymer by the use of low boiling point solvent. The polarity determining unit determines a polarity of the phase current reference. The proximity detection system is configured to determine a distance of a vehicle from a surface of the aircraft and a velocity of the vehicle relative to the aircraft.