||Argon glow discharge lamps are a spin-off from the popular series of neon glow lamps, and once had great popularity particularly in the USA. For many years GE manufactured a number of argon-filled equivalents of its broad range of standard neon glow lamps.
The principal application of argon glow lamps is as a small source of ultraviolet radiation. They have numerous specialised scientific and medical applications, but this particular lamp, the so-called AR-1 (or W1A as it later became known) was sold in large quantities to domestic consumers. During the 1950's one American firm achieved great success in marketing an educational pack of small rocks and mineral specimens having fluorescent properties, the AR-1 lamp being supplied for exciting this fluorescence.
The lamp contains a pair of pressed nickel electrodes, the front surfaces being coated with barium and strontium for good electron emission, and a coating of aluminium powder on the rear half preventing occurrence of the negative glow in that region. Argon is the active gas filling, however it was found that the admixture of around 10% nitrogen greatly extended lamp life and enhanced the UV emission. The principal effect of the nitrogen is to improve the bonding of the Ba and Sr to the surface of the electrode. A gas filling pressure of 10-12 torr was found to yield the strongest UV emission. Due to deterioration of the glass bulb employed in these lamps, the UV output unfortunately falls off quite rapidly during life. The rated life of this argon lamp is 1000 hours to 50% output, much shorter than the 8000 hours of its neon equivalent. Smaller argon lamps, where the bulb is closer to the UV source, have lives as little as 150 hours.