Nuclear Fusion for the future

By the year 2100, human civilization should require 100 times as much power as it consumes today. How will this be provided?

Technologies of higher energy and power density are the path to progress. Just as chemical power—fire, coal, oil, natural gas—dramatically exceeds the yield of physical power—flowing water, blowing wind, the direct motion of people or animals—so the nuclear power of the atom is one million times greater than that of chemical reactions.

Current nuclear power plants operate by fission—the breaking apart of large radioactive nuclei (primarily ura­nium). In nuclear fusion, atomic nuclei such as hydrogen and helium are fused, resulting in a plasma of tens of mil­lions of degrees; this occurs with much higher energy in­tensities and potentially much easier conversion to power on earth, and to rocket thrust in space. On our sun, fusion occurs as nuclei are brought together by the force of the sun's gravitational pull. In order to replicate this force, we use magnets, electron beams, lasers.

A deuterium-tritium (D-T) fusion reaction produces helium-4 nuclei, high energy neutrons, and a tremendous amount of energy when these two types of hydrogen are caused to fuse. Deuterium is plentiful in seawater, and tritium can be produced in nuclear reactors.

A major drawback to the most common fusion reac­tion being researched today—the deuterium-tritium (D-T) reaction—is that one of the products of the reaction is a high-energy neutron (n) particle that cannot be contained by magnetic and electric fields, and creates damage as it flies off.

Lunar Helium-3: Nuclear Fusion Power for the Future

A far superior nuclear fusion fuel is a special isotope of helium, known as helium-3. When fused with deuterium, the products (a proton and a helium-4 nucleus) can be controlled by magnetic fields. No damaging neutron par­ticle, and also means they can more directly be converted into electricity through a process known as magneto­hydrodynamics or used as directed thrust from a rocket. Our sun emits a steady stream of helium-3 particles, which are deflected from Earth’s surface by our magnetic field, but collect in the lunar soil of our Moon.

The preamplifiers of the National Ignition Facility increase the energy of the laser beams that compress and heat fuel pellets to extreme temperatures and densities, triggering nuclear fusion reactions.(Damien Jemison/LLNL)

With nuclear fusion, we overcome limitations im­posed by lower forms of power:

• A lifetime’s supply of electrical power produced from only grams of fuel per person.
• Large-scale desalination and pumping, allowing irrigation of massive tracts of land using ocean wa­ter.
• An entirely new relationship to mining, whereby even low-quality ores (or landfills!) could be produc­tively sifted to draw out useful elements by using a powerful technology called the plasma torch.
• A fundamental expansion of our relationship to the Solar System, where rockets could be fired not only for a few minutes including their takeoff, but for the entire flight, making a journey to Mars, which takes many months under current conditions, a trip of only a week’s duration!

Had fusion been funded at levels mandated by the U.S. Congress in 1985, we would already have a pro­totype reactor. China aims to have the world’s first hybrid fusion-fission nuclear plant by 2030.