Nuclear Fusion

  I do not know with what weapons World War 3 will be fought,
but World War 4 will be fought with sticks and stones.
A. Einstein

RUTHERFORD'S scattering experiment, that was the experiment where alpha particles were directed into the gold foil, presented scientists with some good news and some bad news. The good news: his research team correctly located the place where all of the positive charge was stored in the atom. The bad news revolves around the question: what holds the nucleus together? If the nucleus is made of positive charges that are in very close proximity to one another, the forces of repulsion acting one proton against another must be enormous; so what is the glue that holds these particles together?

So let us consider the simplest multi-particle nucleus on the periodic table. The nucleus of deuterium. it has a single proton
(mass =1.007276 amu) and one neutron (mass =1.008665 amu). It also has one electron(m = .000549 amu).[Remember that 1 amu = 1.67 x 10^-27 kg] These numbers add to m = 2.016494. The rest mass for deuterium is 2.014102 amu, a difference of .002388 amu. The reason why the proton and the neutron do not exist separately is because there's not enough mass to go around. When the this nucleus was formed, the proton and the neutron were driven together so hard that mass was lost, probably converted to energy by fusion. The particles can no longer exist separately because of the insufficiency mass. We can call the insufficiency
nuclear mass defect or nuclear binding energy

A question that probably has caused more consternation than any other throughout the ages is "What is the nature of the furnace that drives the sun?" Given that the estimated rate of energy output is on the order of 10^26 Watts, a chemical process such as oxidation would seem to be out of the question. The mechanism for powering the sun generally accepted today is hydrogen fusion, first suggested in 19XX by nnn The process involves imparting to protons very high kinetic energies, driving them together until they fuse together to make a larger cluster of particles. The energies involved have to be exceedingly large to overcome the Coulomb repulsive forces involved. The hydrogen, probably in plasma form, must exist at temperatures on the order of 10^7 C. The process probably occurs over several steps; it is highly unlikely that four protons would come together at just the right moment. More probable is a chance event that two protons fuse into a deuteron (and release a positron). Subsequently, at another time and place. a deuteron combines with another proton to form a He-3 nucleus. Finally, at still another time and place, two He-3 nuclei combine to form a He-4, and two protons. The net result is that four protons combine to produce a helium atom and two positrons. The masses of the particles before and after are not the same. A small amount of mass is annihilated, producing 26 MeV of energy.

On this planet fusion is the much sought after energy source of choice when compared to fission for three reasons: 1) the fuel (hydrogen) is virtually inexhaustible; 2) the ash is helium (not radioactive, not toxic); 3) the about of energy/nucleon seems advantageous. The bad news is that we cannot contain the fuel at temperatures of 10^7. Work is in progress to achieve this temperature and to cause fusion at a profit. To date, fusion in a reactor has been caused to happen, but the energy input has been greater that the output.

In 1989, two researchers at the University of Idaho announced that they had created cold fusion, the union of hydrogen atoms in a conventional laboratory using simple apparatus. The two principals in the matter, acting more as clever entrepreneurs than as cautious scientists, went to the popular press rather than the more conventional scientific journals. Eventually, the scientific method prevailed and cold fusion was discounted as a hoax, or, at the most charitable, a misunderstanding of the data collected. See an account of this scenario at

We have managed to build a hydrogen fusion device; the hydrogen bomb. It is triggered by a fission bomb. Light metals and metal hydrides are packed in and around the fission material. When the conventional explosive trigger detonates and implodes, the fissionable material reaches critical mass and critical array and the chain reaction is initiated. The energy produced at the core of this reaction causes the temperature to increase until the fusible material is driven together. The first thermonuclear device (so-called because of the high temperatures involved) was detonated at Eniwetok Atoll in the pacific in 1952. This device packed considerably more punch than the fission bomb. The latter has a critical array issue; the explosion pushes the fissionable material away until the likelihood of a fission event drops to zero.

Fortunately for living creatures on this planet, we have managed to avoid using a hydrogen device in any kind of conflict. At this stage of development, a thermonuclear war would kill everything. In 1945, the Hiroshima bomb had the destructive capability of 10^4 tons and was delivered by an airplane moving at 10^2 mi/hr. Let's call this a destruction index 10^4 x 10^2 = 10^6. By 1960, (in less than one generation) the destructive equivalence had increased to 10^8 tons delivered by missiles moving at 10^3 mi/hr. This yields a destruction index of 10^11. In the space of 15 years, our ability to deliver destruction has increased by a factor of 100,000. Clearly, at no time in history has weaponry increased at such a devastating rate.,17,17

cold fusion

last edited 12/29/05

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