Hydrogen solar fusion

Solar fusion Nuclear fusion reactions are responsible for the glow and heat from stars such as the Sun. The temperature of the Sun s core Is about 15,000,000 K. It is so hot and dense that hydrogen nuclei fuse to produce helium. After billions of years, the Sun s hydrogen will be mostly depleted. Its temperature will rise to about 100,000,000 K, and the fusion process will then change helium into carbon. 

The helium content of ambient air amounts to 5.24 ppm. The total quantity of helium in the atmosphere is in a stationary equilibrium between the gas escaping into space on the one hand and the helium supplied by radioactive minerals and the solar wind on the other hand [4.2], In the sun, helium is represented with a molar fraction of about 8%, whereas hydrogen amounts to about 92%. In the universe, helium is the second most abundant element wdth a molar fraction of more than 25%. Helium is an end product of the hydrogen-nuclear fusion in fixed stars [4.1]. 

In many cases, the deposited material can retain some of the original chemical constituents, such as hydrogen in siUcon from the deposition from silane, or chlorine in tungsten from the deposition from WCl. This can be beneficial or detrimental. For example, the retention of hydrogen in siUcon allows the deposition of amorphous siUcon, a-Si H, which is used in solar cells, but the retention of chlorine in tungsten is detrimental to subsequent fusion welding of the tungsten. 

At 2000 K there is sufficient energy to make the H2 molecules dissociate, breaking the chemical bond the core density is of order 1026 m-3 and the total diameter of the star is of order 200 AU or about the size of the entire solar system. The temperature rise increases the molecular dissociation, promoting electrons within the hydrogen atoms until ionisation occurs. Finally, at 106 K the bare protons are colliding with sufficient energy to induce nuclear fusion processes and the protostar develops a solar wind. The solar wind constitutes outbursts of material that shake off the dust jacket and the star begins to shine. 

In stars with masses greater than 1.2 times the solar mass, hydrogen fusion proceeds via another channel, the so-called CNO cycle. This process tags together proton captures and () decays in the following chain of reactions ... 

Hydrogen fusion via either the proton-proton chain or the CNO cycle in the centre of stars comes to an end when most of the hydrogen has been transformed into helium. Helium fusion produces two elements essential to life, namely carbon and oxygen. In fact, carbon constitutes 18% of our bodies, and oxygen 65%, whilst the fractions of these same elements in solar material are just 0.39% and 0.85%, respectively. Only hydrogen and helium are more abundant in the Sun. 

Solar thermonuclear fusion transforms hydrogen into helium. 

Energy sources and conversion— biomass, batteries, fuel celts and fuel cell technology, hydrogen as a fuel, liquid and gaseous fuels from coal, oil shale, tar sands, nuclear fission and fusion, lithium lor thermonuclear reactors, insulating materials, and solar energy. 

Debris from earlier supemova(s) condensed into the Solar Nebula about 6 billion years ago (Faure, 1998, 22). By about 4.5 billion years ago, the planets had largely condensed from the nebula and the core of the Sun became dense enough to ignite through fusion Reaction 3.1. Based on the chemistry of chondrite meteorites (Wasson and Kallemeyn, 1988, 536), the original Solar Nebula had about 6.79 arsenic atoms for every one million atoms of silicon (Table 3.1) and 2.72 x 1010 atoms of hydrogen (Faure, 1998 Anders and Ebihara, 1982, 15). 

Never mind. In the center of the Sun is the core, the Sun s power plant in which nuclear fusion reactions turn hydrogen into helium and generate tremendous amounts of heat. Here, the gas density is more than 100 times that of water, or 14 times that of lead. In fact, the core contains 40 percent of the solar mass. 2 Sir, at that density, why isn t the core a solid ... 

On solar scales, the change is slow. It takes a billion years for only 0.01 percent of the Sun s mass to metamorphose into beautiful sunshine. The Sun s nuclear reactions are slowed because the positively charged protons repel each other. This repulsion slows down the fusion. If the rate were much quicker, the Sun would explode like a big hydrogen bomb. 

The possibility of the formation of gaseous reaction products in ion-bombarded solids exists either in the case of two different implanted elements reacting with each other or the implanted ions reacting with constituents of the target. There are two fields where such reactions play a major role. The first one is the fusion research where one expects hydrogen to react with the wall constituents of a fusion reactor, the second one is cosmochemistry where one knows that solar wind reacts at the surface of the moon or planets. In both cases the ion implantation technique is able to simulate the real processes. 

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