Nuclear Fusion Definition

Nuclear Fusion creates loads of energy. In technical terms it is when two lighter atoms join (or fuse) together in extreme temperatures to create one heavy atom. When you look at the sun or the stars in the sky that is exactly what you are seeing, nuclear fusion in action.

The fusion of the nuclei of two atoms of Hydrogen results in the creation of Helium. This may not sound too exciting but with any nuclear reaction there will be a release of energy. In the case of nuclear fusion, a huge amount of energy. As a comparison nuclear fission results in 1.2 million times the energy of coal or TNT. Amazingly nuclear fusion produces 3–4 times that of nuclear fission.

Nuclear fusion is already used within thermonuclear bombs in combination with nuclear fission. However, the holy grail of the nuclear industry is to generate electricity using a nuclear fusion reactor. This has been something that has been sought for decades.

Nuclear fusion as a source of energy would be such a big step forward. The fuel would be hydrogen with the waste product helium. This is worlds away from the current fossil or nuclear fuels technologies. There has been some success and development continues to progress but there is no solution to this challenge just yet.

Fusion Energy And Technology Types Explained

Nuclear fusion comes with a promise of a solution to the world’s climate change issues. However, there is one technical hurdle that needs to be overcome. For lightweight atoms to fuse and release energy they need to be brought together In millions of degrees heat.

In fact, the goal of a fusion reactor is to achieve fusion plasma. This is an enormous cloud of rolling atoms that are hotter than the sun. The nuclear plasma needs to be generated and kept under control using less energy than the fusion reactor produces.

As such, fusion power has been ‘a couple’ of decades away for almost a century.

There are currently several designs under development, the majority of which are based on a tomamak design. By utilising a donut shaped design, the tokomak allows for the plasma cloud to be confined by magnetic forces. This will allow for containment of the reaction of two isotopes of hydrogen at 100,000,000 degrees centigrade. This is known as magnetic confinement.

Other designs include inertial confinement fusion (ICF), Magnetic or electric pinches and inertial electrostatic confinement. They all take more energy to run than they produce. There is optimism that this will change soon.

Nuclear fusion has an interesting past. It all started in 1932 with the first demonstration of fusion in a Laboratory by Mark Oliphant. Fast forward to 2020 the MAST achieved plasma claiming ‘game-changing’ improvements to fusion technology. The story has yet to make a conclusion. In fact it feels like it is only just beginning.

You can find a timeline of all of the major occurrences in the lifecycle of fusion reactor development. This can be found at wikipedia. We have put together a much more succinct version of events below. This should be enough info to give you the inspiration to apply for one of the many roles supporting the pursuit of nuclear fusion reactor technology.

The actual first attempt to make a working fusion reactor was in 1938. However, the NACA Langley Research Center attempt was unsuccessful. The UK’s ZETA device at Harwell claimed fusion in 1958, this was later withdrawn following challenge. However, later in the same year the first controlled thermonuclear fusion in any laboratory was achieved by Scylla I. However the pinch approach used by Scylla was abandoned as it was not possible to scale up to produce a reactor.

In the nuclear deterrence arena 1952 saw the first detonation of a thermonuclear bomb. The bomb released 10.4 megatons of TNT out of fusion fuel. In 1961 the Tsar Bomba was tested by the Soviet Union. At 50 megatons it remains the most power weapon ever dropped.

It was in 1955 that it was first predicted that fusion will be ready for commercial use in just two decades. This was made by Homi J. Bhabha at that years Atoms for Peace. This stirred a number of countries into action to start fusion programs of their own. The race to first fusion plasma began.

It was not until 1964 when plasma temperatures approximating 40 million degrees Celsius were achieved. It was the Scylla IV that was to achieve this at the LANL facility in Los Alomos, New Mexico. In the meantime in 1960 the concept for inertial confinement fusion (ICF) was published by John Nuckolls. Nuclear fusion was starting to look like an exciting place to be in the early 1960's.

This was short-lived. At an international meeting in 1965 it was clear the most fusion efforts had stalled. The Soviets provided results showing great improvements in their toroidal pinch machines which is almost identical to the ZETA design. At the same meeting ZETA reported some strange results. All major designs at this point are losing plasma at too high of a rate to be utilised in a reactor.

Three years later in 1968 the Soviet claim temperatures higher than any other by an order of magnitude. This is for their T-3 tokamak which is similar to their toroidal pinch machine and ZETA. This is of course met with scepticism. However, the Soviets did were confident and invited a UK team — “The Culham Five” — to confirm the results for themselves. They published their results in late 1969 confirming the results. This lead to an increase in tokamak construction all over the globe.

It was not until 1975 when the Princeton Large Torus (PLT) commenced operation. Quickly setting many records. The PLT surpassed any machines that had gone in the past. These results led to the US DOE providing the funding for a Tokamak Fusion Test Reactor (TFTR) in 1976. The PLT continues to set new records and in 1978 Princeton is given additional funding to further adapt TFTR with the explicit goal of reaching breakeven.

It was then not until the 1980’s that progress of note was made. In 1983 the Joint European Torus (JET) based in Culham, UK achieved first plasma. The project was the largest magnetic confinement plasma physics experient ever. Commencing design work in 1973 it was completed on time and on budget.

In 1985 the Japanese tokamak, JT-60 achieved first plasma. In 1988 the Tore Supra in Cadarache, France utilising superconducting magnets achieved first plasma. Additionally in 1988 the concept design for ITER (International Thermonuclear Experimental Reactor) commences. This will be a successor for JT-60, T-15, JET and TFTR. ITER is a collaboration between many countries across the world.

One year later in 1989 a huge 10 beam NOVA laser at LLNL, California is completed and produces 120 kilojoules of infrared laster light during a pulse experiment. In this year two electrochemists from Utah made an announcement that they had achieved cold fusion. This indicated that they could achieve fusion at room temperature. However, peer reviews of their work found no credit to their claims.

The 1990’s provided many successes and developments in the nuclear fusion space. in 1991 the START (Small Tight Aspect Ratio Tokamak) fusion experiment at Fulham achieved a record result adapting the conventional toroidal fusion experienments into a higher spherical design. In 1993 the TFTR successfully produced 10 megawatts of power from a controlled fusion reactor. Then in 1996 utilising actively cooled plasma-facing components the French Tore Supra generated 2.3 megawatts for a duration of 2 minutes.

The JET tokamak went on to produce a world record 16 megawatts of fusion power in 1997. Four megawatts of self-heating was also achieved. Self-heating is an expression regarding a fusion energy gain factor. The ratio of power being released by a fusion reactor versus the energy needed to power the reactor is expressed as Q. When Q is great than 1 it is said that the fusion reactor is self-heating.

One year later in 1998 the Japanese JT-60 tokamak produced a high performance shear plasma. This is the current world record of a 1.25 Q fusion energy gain factor. A momentous decade for nuclear fusion was completed in the news in 1999 that the START experience was to be superseded by MAST (Mega Ampere Spherical Tokamak).

Following all the developments of the 1990’s. The first half of the first decade of the new millennia didn’t produce too much to note. There was a little excitement in 2002 when claims were made about small-scale fusion using acoustic cavitation. This will quick dismissed. The ITER project finally made the decision that it would be sited in Cadarache in France in 2003.

The back-end of the decade started promisingly with NIF firing its first bundle of eight beams. The National Ignition Facility (NIF) is located at the Lawrence LLNL, California. It is a large laser-based inertial confinement fusion (ICF) research device. This achieved the highest ever energy laser pulse of 152.8 kJ in 2005.

The following year in 2006 China’s test reactor, the first to use superconducting magnets is completed. It is called EAST (Experimental Advanced Superconducting Tokamak). At the Heavy Ion Fusion (HIF) Symposium in 2010 in Germany there is a presentation in which it is claimed that HIF will be commercial within the decade.

The 2010’s brought more development and progression. However, fusion continued to remain to be a couple of decades away. In 2012 JET announced a breakthrough in controlling instabilities in fusion plasma. The following year EAST records a confinement time of 30 seconds for H-mode plasma thanks to heat dispersal of tokamak wall improvements. Then, in 2014 there is progress in generating more energy then is used to generate fusion. This was achieved at NIF in the US.

2015 saw the Stellarator Wendelstein 7-X in Germany achieve first steady state plasma. This is by utilising a large-scale stellarator design. In the same year Polywell was present at Microsoft Research. This was a proposed fusion reactor design. It is still in development. However, in 2019 the University of Sydney produced research to show the design in practice is impossible.

Also in 2015, the ARC (affordable, robust, compact) fusion reactor is announced by MIT. The ARC design claims to utilise a smaller configuration than other designs whilst maintaining a similar magnetic field. In 2016 the Wendelstein 7-X device produced if first hydrogen plasma.

The following year in 2017 there was quite a bit of movement. China’s EAST achieves over 100 seconds of steady-state high confinement plasma. Helion Energy’s plasma machine, The Fusion Engine goes into operation. The Tokamak Energy ST40 generates its first plasma in the UK. Also, it is announced that the Norman reactor has achieved plasma by TAE Technologies.

The momentum continued in 2018 with TAE Technologies announcing that its fusion reactor had achieved 20 million degrees Celsius. Commonwealth Fusion Systems is provided investment by Eni. The aim is commercialise SPARC in a collaboration with MIT and utilising ARC technology. Also during the same year MIT scientists formulate a theory to remove excess heat from compact fusion reactors and General Fusion begins developing a 70% scale demo which will be ready in 2023.

As we approach the present day in 2017 the announcement was made on the STEP (Spherical Tokamak for Energy Production) facility. This investment has been made by the UK with the aim of having a fusion facility in 2040. Which is just a couple of decades away. Finally in the following year, in 2020 the first plasma was achieved at UK’s MAST tokamak. The MAST is the forerunner to the STEP and the success trial is seen as a ‘game-changer’ when it comes to being able to extract excess heat.

Nuclear Fusion and Nuclear Fission are both physical processes that produce energy from atoms. As described above Nuclear Fusion occurs when lighter atoms join (or fuse). Nuclear Fission occurs when a heavy atom is split. Both create loads of energy.

The main difference of Nuclear Fusion and Nuclear Fission are the fuel types, by-products, amount of energy released and technology availability.

Nuclear Energy Fuels Types; Nuclear Fusion uses Hydrogen whereas Nuclear Fission uses Uranium or Plutonium.

Nuclear Energy By-Products; Nuclear Fusion releases Helium as a by-product. Nuclear Fission result in spent nuclear fuel. This is known as nuclear waste and needs to be stored securely for many years.

The energy release of Nuclear Energy; Nuclear Fission produces energy 1 million times that of other source such as coal. Nuclear Fusion releases 3–4 times that of nuclear fission.

Nuclear Energy technology availability; Nuclear Fission has been in use since the 1950’s. There continue to be development work to make the technology safer, more efficient and to reduce production costs. Nuclear Fusion is the holy grail of the nuclear industry. Development has been ongoing since the 1930’s. It is current aims that we have a nuclear fusion reactor producing electricity by 2040.

Originally published at https://www.getintonuclear.com on November 30, 2020.