Patent ID: 8390197

Claim:
A long arc column discharge tube comprising: a hermetically sealed container containing a gas and made from a non-conductive material coated to be impermeable to the gas contained therein; a light exit window in the hermetically sealed container; an anode residing in the hermetically sealed container; a cathode residing in the hermetically sealed container; a long column structure residing in the hermetically sealed container, the long column structure including: a narrow passage through the center of the long column structure; a first discharge path in the narrow passage, the first discharge path creating light discharged from the narrow passage through the light exit window, wherein the discharged light is proportional to a gas density in the hermetically sealed container and is proportional to electric discharge current in the gas; and the first discharge path having a narrow column between the anode and cathode, wherein the length of the narrow column enables summation of light emitting photons along the narrow column length, and the length of the narrow column in conjunction with the diameter of the narrow column, shapes the light output from the first discharge path.