The Breakthrough in Nuclear Fusion

Hello readers! Today's blog post will be about nuclear fusion, inspired after I read a recent article on a new breakthrough in nuclear fusion. It has been reported that US researchers have achieved a world first in an ambitious experiment that aims to recreate the conditions that occurs in the deep core of the sun and will pave the way for new nuclear fusion reactors. They generated more energy from fusion reactions than they put in the nuclear fuel, which is a crucial step to harnessing fusion power. The ultimate goal of this experiment is to produce more energy than the whole experiment consumes which still remains a long way off, but this feat has raised hopes after decades of setbacks and how progress is finally being made. Their experiments, at the National Ignition Facility at the Lawrence Livermore National Laboratory in California, used a bank of 192 powerful lasers to crush a minuscule amount of fuel so hard and fast that it becomes hotter than the sun. During the experiment, they managed to produce from the fusion reactions in the fuel, 17 kilojoules of energy was released.    



So what is nuclear fusion?

It is the process of making a single heavy nucleus from two lighter nuclei. This process is called a nuclear reaction which releases a large amount of energy. The nucleus made by fusion is heavier than either of the starting nuclei. It is not as heavy as the original mass of the starting nuclei. This lost mass is due to the energy produced. (and lost from the mass, it has changed into lots of energy). Fusion is what happens in the middle of stars, for example, the Sun. Hydrogen atoms are fused together to make helium. This releases lots of energy which powers the heat and light of the start. Not all elements can be joined; heavier elements are less easily joined than lighter ones, for example, iron cannot fuse with other atoms. This is what cases stars to die. Stars join all their atoms together to make heavier atoms of different types until they start to make iron, which causes the reactions to stop, and the start to cool down and die. It is very difficult to recreate nuclear fusion reactions on Earth that release more energy than is needed to start the reaction. The only successful approach so far has been in nuclear weapons. The hydrogen bomb uses an atomic bomb in order to start fusion reactions. However, in order to use the reaction as a clean source of energy, there is still a lot of challenges and hurdles facing scientists before it can be a viable source.  

How does it work?

• In nuclear fission, you get energy from splitting one atom into two atoms. In an nuclear reactor, high-energy neutrons split heavy atoms of uranium, yielding large amounts of energy, radiation and radioactive wastes that lasts for a long time
• In nuclear fusion, you get energy when two atoms join together to form one. In a fusion reactor, hydrogen atoms come together to form helium atoms, neutrons and vast amounts of energy. It would be a cleaner, safer and more efficient and abundant source of power than nuclear fission
• There are several types of fusion reactions and most involve the isotopes of hydrogen called deuterium and tritium: a proton-proton chain which is a sequence used by stars such as the sun. Two pairs of protons form to make two deuterium atoms. Each deuterium atom combines with a proton to form a helium-3 atom. Two helium-3 combine to form beryllium-6, which is unstable. Beryllium-6 decays into two helium-4 atoms. These reactions produce high energy particles (protons, electrons, nuetrinos, positrons), and radiation (light, gamma rays).  
• There is also deuterium-deuterium reactions which involve two deuterium atoms combine to form a helium-3 atom and a neutron. There is also deuterium-tritium reactions where one atom of deuterium and one atom of tritium combine to form a helium-4 atom and a neutron. Most of the energy released is in the form of the high-energy neutron.
• Conditions for nuclear fusion: high temperature, which gives the hydrogen atoms enough energy to overcome the electrical repulsion between the protons. Fusion requires temperatures about 100 million Kelvin (approximately six times hotter than the sun's core), and at this temperature, hydrogen is a plasma, not a gas. Plasma is a high-energy state of matter in which all the electrons are stripped from atoms and move freely about. The sun achieves these temperatures by its large mass and the force of gravity compressing this mass in the core. We must use energy from microwaves, lasers and ion particles to achieve these temperatures. Another condition is high pressure, which squeezes the hydrogen atoms together and they must be within 1x10-15 meters of each other to fuse. The sun uses its mass and force of gravity to squeeze hydrogen atoms together in its core, so we must squeeze hydrogen atoms together using intense magnetic fields, powerful lasers or ion beams.

Thanks for reading!