Nuclear Fusion: Progress, Problems, and Possibility

By Harrison York


Image Credit: Flickr @ herbert haseneder

What is Nuclear Fusion?

Nuclear fusion is a natural phenomenon necessary for life. The sun, and all other stars in the universe, have produced light and heat for billions of years as a result of the fusion process. Fusion occurs within stars because of immense pressure and heat present with the enormous amounts of matter gathered in a celestial body. The extreme pressure and heat (up to 15 billion degrees Celsius in our sun’s core) cause the atoms making up stars to accelerate - the temperature and motion of atoms are directly proportional - and collide. These hydrogen atoms slam into each other at such a speed that the electrostatic force repelling the two positive nuclei of the atoms is overcome, and the atoms fuse. From two atoms with one proton, each emerges one atom with two protons: helium. While the new helium atom is a product of the fusion of the two hydrogen atoms, its mass is not exactly the same as the initial mass. Where, then, does this mass go? This small amount of mass is converted into energy, as described in Einstein’s famous equation: E=mc2, where m is mass, E is energy, and c is the speed of light. Clearly, the small amount of mass lost equates to a massive amount of energy. Each second, the sun is able to convert 600 million tons of hydrogen into helium, providing our planet with warmth and energy.


Fusion on Earth

Because of the immense amounts of energy produced by the sun during the fusion process, it would seem that fusion is an ideal energy source. First, fusion utilizes hydrogen, an abundant element that exists on Earth in seawater, and produces helium as a byproduct, a harmless, colorless, odorless gas that floats away and dissipates into the atmosphere. So, fusion uses common substances with minimal pollution as a result. Secondly, fusion is a relatively safe process compared to nuclear fission - the process by which radioactive elements undergo radioactive decay under a controlled setting in order to produce energy - where hazardous waste is created with no easy solution as to where this waste can or should be stored. Third, fusion has the potential to provide a stable and strong source of on-demand energy cleanly and, with advancements, efficiency. Alongside renewable energy sources, like solar panels, which also create energy from the nuclear fusion process in the sun, and battery energy storage, nuclear fusion can contribute to a transition away from fossil fuels and towards an environmentally-friendly future.


Image Credit: Flickr @ Timitrius

The Process and Progress

Gradually, progress is being made by universities, research companies, and various manufacturers towards the future of fusion. Increasingly strong magnets are being manufactured in order to hold plasma in fusion chambers, and funding is given to research and development for several ventures looking to create practical energy solutions using fusion. The process by which fusion occurs in a lab has several parts. In theory, once the extreme temperature of 150 billion degrees Celsius has been reached through the heating of plasma and can be maintained, an atom of Deuterium and Tritium collide, producing an atom of helium, an excess neutron, and a large amount of energy. Deuterium and Tritium are simply isotopes of hydrogen, or a hydrogen atom that has one and two neutrons, respectively. These isotopes are abundant in seawater and can be extracted from lithium. In order to create fusion in the lab, besides heat, two other needs must be met. Superheated gas loses its electrons, becoming an ionized state of matter known as plasma. This plasma must be kept at the proper particle density to increase the probability that fusion collisions occur. Next, this plasma has to be confined to an extended amount of time in spite of plasma’s tendency to expand. To solve this, scientists have devised a device called a tokamak which uses magnetic fields to contain the gas. Tokamaks are ideally able to heat up the gas and allow it to accelerate in a confined place to the point where fusion occurs. The energy created in the process is split unequally between the helium atom and the neutron products. After being created in the fusion process, the helium atom remains in the plasma, and its energy contributes to the sustained heating of the tokamak chamber. The neutron, however, has no charge and, unlike the plasma and helium, is not bound in the magnetic field of the tokamak. The neutrons, carrying about 80 percent of the energy produced in each fusion occurrence, hit the walls of the chamber where the kinetic energy is changed into heat energy. This heat is transferred into a circulating water container surrounding the walls, which then creates heat and powers turbines. In this way, the massive potential of nuclear fusion can be utilized in a new way of creating clean, sustainable energy.

Obstacles on the Road to Fusion

Despite the positive benefits of nuclear fusion, it has not yet become effective enough to begin producing energy for our energy-demanding world. To begin, Earth lacks the pressure at the core of the sun, which requires fusion chamber temperatures to operate at about ten times the temperature of the sun’s core: 150 billion degrees Celsius. Another issue is the hurdle of creating a net energy gain fusion reactor. This is a system that consistently produces more energy than it consumes, and it is vital if any future for fusion is to be realized. Additionally, a strong magnetic field must be created in a tokamak, a torus-shaped fusion chamber, in order for the plasma to be held in place for a sufficient amount of time. This requires strong magnets and energy as the plasma is initially heated and sent into the main chamber. Next, the entire process of manufacturing tokamaks, magnets, and the equipment needed for a fusion reactor is expensive. More research must take place and funding must continue for success to be reached. While fusion is a very real future - one that we are sure to reach - fusion reactors will not be producing energy for your home tomorrow.


The Future of Fusion

Fusion is a very possible way of creating energy, however far we are from it, and, as long as continual research and work are made for the development of fusion technology, the goal of a net energy gain system will most likely be reached in several decades, with optimistic estimates predicting viable fusion machines around 2030. There is still work to be done and time and money to be spent before nuclear fusion becomes a daily driver for our planet, but it is a very real and a very exciting future.


Comprehension Questions:


1. What is the basic fusion process and where does it occur naturally?

The fusion process involves hydrogen atoms, under either immense heat and pressure (in a star), or an even greater amount of heat (on Earth) colliding and fusing together. This creates a helium atom with the two protons from the hydrogen atom, an extra neutron, and a large amount of energy because of the conversion of a small amount of mass. The fusion process occurs naturally in the cores of stars, which is why they produce heat, light, and energy.


2. What are the benefits of nuclear fusion?

Nuclear fusion as an energy source is beneficial to our society because it consumes common substances, like seawater, as a source of hydrogen, and produces helium, neutrons, and energy as a direct result. Steam is also produced indirectly as water is heated from the fusion process. Next, fusion, because of the harmless byproducts produced, does not harm the environment and can help the world transition to sustainable energy sources. Fusion is also, when refined enough, able to provide a stable, constant source of energy to the world. Fusion has the potential to create large amounts of energy through the conversion of mass into energy.



Citations:


https://www.iter.org/sci/whatisfusion


https://www.iter.org/sci/makingitwork


https://generalfusion.com/what-are-the-benefits-of-fusion-energy/


https://www.forbes.com/sites/arielcohen/2019/01/14/is-fusion-power-within-our-grasp/#7506191f9bb4


https://www.euro-fusion.org/fusion/fusion-on-earth/


Image Citations:

https://rb.gy/rrbtqb

https://rb.gy/8el2bl


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