Cold Cathode Fluorescent Lighting.

Cold Cathode Fluorescent Lighting.: "Fluorescent lighting operates at several times the efficiency of incandescent lamps and is important for energy conservation, especially in photovoltaic power systems where electricity generation and storage costs are relatively high. Even small improvements in lamp efficiency can offset substantial capital and operating expenses for solar lighting systems. Conventional fluorescent lamps apply a voltage between heated electrodes located at each end of the tube, creating an electric arc discharge. Special gasses in the tube emit ultraviolet light that stimulates fluorescence of the phosphors lining the inside of the tube. Correct electrode temperature is crucial to the longevity of the lamps which are rapidly degraded by variations from their optimum input voltage and ambient temperature. This is a major problem for extra-low-voltage lighting systems using storage batteries. Nominal 'twelve-volt' batteries typically reach 15 volts during boost phases and below 11 Volts when discharged. Many fluorescent lamps overheat and fail if operated at 15 volts for more than a few minutes. Low voltages damage the tube electrodes due to insufficient heating, resulting in internal tube blackening and a decline in phosphor efficiency. Even under ideal conditions, the electrodes slowly accumulate damage from the electric arc discharge. Material is slowly vaporised from the electrodes and deposited on the inside of the tube, degrading the phosphors and causing most of the characteristic decline in light output as the tube ages. The heated electrodes are also a substantial contribution to the energy consumption of the lamp. Consequently, fluorescent lamp efficiency is generally a function of size. Large lamps are more efficient, in part because a smaller proportion of energy is used to heat the electrodes in a longer tube."