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"The Properties of NHe64*" Meta is an optoatomic cluster-molecule known more properly as nitro-stabilized metastable helium, also called nitrometahelium by the atomic scientists, Meta was the name adopted by SF engineers.. Meta is a strange molecule, with a structure somewhere between that of a buckyball and a bunch of grapes. At the core of a meta cluster is a single atom of excited nitrogen, surrounded by sixty-four helium atoms, each atom with one of its electrons raised into a more energetic metastable state. Metastable helium has always been easy to form--just pass some high voltage electricity through helium gas. Large amounts of metastable helium atoms existed in every neon sign and the helium-neon lasers in grocery store checkout stands on 20th century earth. Its also been known that if metastable helium could be stored, it would make a superb rocket fuel, since it contains more energy per kilogram than most other materials. If left to itself, a metastable helium atom would have a lifetime of two and a half hours, but if you crowded the atoms together in a fuel tank, the lifetime dropped to a fraction of a second, making the stuff useless as a rocket fuel. Scientists made the compound by merging beams of helium and nitrogen atoms, and excited the atoms into their metastable states with lasers, that the metastable helium atoms would cluster around the nitrogen atoms. The cluster constructed of sixty-four metastable helium atoms surrounding a single excited nitrogen atom turned out to be exceptionally stable. In some strange, still not understood way, the single nitrogen atom completely stabilizes the excited helium atoms. The meta clusters are readily condensed into a liquid. Best of all, the liquid meta can be handled and stored over a wide range of temperatures without danger of explosion. Even the occasional cosmic ray can`t trigger a chain reaction. When meta is heated beyond 2200 K, however, the clusters disintegrate. Milliseconds later, the sixty-four helium atoms from the cluster release their stored energy, creating a blazing blue plasma of ionized helium gas along with the occasional nitrogen atom. Specialized magnetoshielded rocket engines are used to cope with the energetic new fuel, but fortunately, meta also has a high heat capacity, so it can be used to cool the exhaust nozzle before being "burned" in the reaction chamber. The exhaust velocities attained exceed 100 kilometers per second, more than six times that of MHD thrusters. As a side note, passing meta through a charge-reversal device to produce antimeta would provide a valuable alternative to the deuterium\antideuterium reactions currently used. The only problem is that it requires more energy to pass meta through a CR device than deuterium. |
