Luminous paint paint was used to illuminate Apollo Lunar Module electrical switch tips and painted on control panels of the Lunar Roving Vehicle. The latest generation of the radioluminescent materials is based on tritium, a radioactive isotope of hydrogen with half-life of 12.32 years that emits very low-energy beta radiation. The devices are similar to a fluorescent tube in construction, as they consist of a hermetically sealed (usually borosilicate-glass) tube, coated inside with a phosphor, and filled with tritium. They are known under many names – e.g. gaseous tritium light source (GTLS), traser, betalight. Tritium light sources are most often seen as
Tritium neutrons. As the fission fuel depletes and also explodes outward, it falls below the density needed to stay critical by itself, but the fusion neutrons make the fission process progress faster and continue longer than it would without boosting. Increased yield comes overwhelmingly from the increase in fission. The energy released by the fusion itself is much smaller because the amount of fusion fuel is so much smaller. The effects of boosting include: The tritium in a warhead is continually undergoing radioactive decay, hence becoming unavailable for fusion. Furthermore its decay product, helium-3, absorbs neutrons if exposed to the ones