they do it artificial sun Because it’s the same source of energy that our closest stars use. Nuclear fusion-in fact clean energy A source that the great powers have pursued for decades. Fifty years ago, experts said he had only fifty years to do it.
However, it seems that China is close to breaking the record for the longest fusion reaction.—101 seconds at 120 million degrees Celsius.
This article will cover:
What is nuclear fusion and the artificial sun?
First, let me explain what is nuclear fusionConventional nuclear power plants work by releasing energy from nuclear fission. That is, by “shattering” the atoms. Neutron-irradiated enriched uranium is used to start nuclear chain reactions.
These plants have been in operation for over half a century.In particular, the USSR opened the first nuclear power plant connected to the power grid 1954But it is not without risks, as explained in our series on the Chernobyl accident.
on the one hand, uncontrolled chain reactionAlthough the consequences are devastating, this kind of event is highly unusual. The real problem with nuclear fission lies in the waste products produced. Maintaining Dangerous Radioactivity Levels for Centuries.
In contrast, nuclear fusion and the artificial sun Generate energy safely And it’s almost wasteless. Due to its low carbon footprint, it can be a powerful tool against climate change.
How is this achieved? essentially, Fusing two light nuclei into one heavy nucleus under high pressure and temperatureThis reaction also releases energy because the resulting nucleus has less mass than the first two separate nuclei.
“Deuterium in 1 liter of seawater can produce the equivalent of 300 liters of oil.”
The fuels typically used to create artificial suns are based on deuterium and tritium isotopes. Deuterium can be extracted from seawater, and tritium from lithium. Both elements are absolutely abundant and virtually limitless compared to uranium.For example, deuterium in 1 liter of seawater is Produces energy equivalent to 300 liters of oil.
To get an idea of the energy released in the fusion process, it is enough to note that a few grams of fuel can produce 1 terajoule.—enough to cover Amount of energy needed by one person every six years in developed countries.
Does nuclear fusion produce radioactive waste?
no. Nuclear fusion reactions also produce waste. Most of it is helium, which is an inert gas. However, tritium also produces a small amount of radioactive waste.
Fortunately, they decay much faster than their fission counterparts.In particular, they can reuse or recycle within a hundred years.
In addition, the neutron flux produced in the fusion process can affect surrounding matter, gradually becoming radioactive in the absence of shielding. Shielding of the reactor structure is therefore another important aspect.
How the artificial sun works
OK, we already have tritium and deuterium fuels and the basic working principle. But how does the process work? Now, this is where the pitfalls begin when moving from theory to practice.
As already mentioned, very high pressures and temperatures must be applied. enough to turn the fuel into a very hot plasma.atom is collide with each other at a temperature of at least 100 million degrees Celsius and Sufficient pressure to bring them so close that nuclear attraction exceeds electrical repulsion.
It’s like overcoming the repulsive force of two magnets of the same polarity to glue them together and draw roughly parallel lines.
To achieve these extreme conditions, magnetic fields and powerful laser beams are focused on the fuel. Once you reach the super hot plasma state, you need to keep adding fuel. high heat release It must be contained without destroying the reactor.
Of course, no material can withstand 100 million degrees Celsius without melting instantly.Here is plasma confinement It is achieved by different types of reactors as detailed at the end of the article.
Latest fusion breakthrough
As mentioned earlier, one of them is The latest breakthrough in nuclear fusion I’m from China. In May 2021, a researcher at the Southwestern Physical Laboratory (swap) announced that its HL-2M nuclear reactor in Chengdu, China has broken all records for fusion experiments.
It’s a complex process, but the biggest challenge isn’t fusion itself, which many reactors have achieved in recent years.the real challenge is keep it up over time: Few have managed to exceed a few seconds.
And SWIP scientists won a medal for reaching 150 million degrees Celsius.s for 101 secondsThe previous record held by South Korea was 20 seconds.
Tokamak reactors are called “artificial suns”, but they are actually 10 times hotter than the core of the sunAttention is now focused on the hottest international projects. ITERThis gigantic project involving 35 countries has just completed its first construction phase. If all goes well, the final reactor he will produce 500 MW by 2035.
What is the most common fusion reactor?
Like HL-2M, ITER is a tokamak reactor, one of several designs currently being tested. The classification of fusion reactors is mainly defined by the type of plasma confinement and the plasma heating method.as indicated by International Atomic Energy Associationthe following fusion technologies can be mentioned:
- magnetic confinement
- inertial confinement
- Magnetic Inertial Fusion (MTF)
- hybrid fusion
magnetic confinement
This technique is the most common and uses powerful electromagnets to confine the plasma. Current and auxiliary system such as microwaves and accelerated particles. The magnetic field used is toroidal. This term comes from the mathematical term “torus”, which means donut.
The design comes from Russian physicists Sakharov and Tam, who designed the first tokamak in 1951. Depending on the shape of the confinement chamber and the type of electromagnet, these fusion reactors he can be divided into four types.
- Tokamakthe classic “doughnut” reactor
- stellarizer
- Opposite field magnetic pinch (RFP)
- compact toroid
inertial confinement
This type of confinement is one of the newest lines of research. Used in nuclear reactors such as the National Ignition Facility (NIF) United States or first light fusion In the UK, they use hundreds of laser beams or generate shock waves to compress microcapsules of fuel.
For NIF, frozen deuterium and tritium microcapsules are irradiated with 192 ultraviolet laser beams.
So far, NIF has achieved only billionths of a second ignition, but the first photo-fusion project still in early stages of development.
Magnetic Inertial Fusion (MTF)
As the name suggests, these reactors Combining a toroidal reactor with an inertial confinement functionAlthough the first proposals for this design date back to the 1970s, it was only in this decade that MTF technology gained momentum. Several companies are currently working on his experimental MTF reactor.
Like a tokamak, the plasma is confined using a magnetic field. However, the heating is provided by a series of giant pistons that generate shock waves. You can see the model MTF reactor in action. this video.
hybrid fusion
this type of reactor combine fission reactors covering the core where the fusion process occursIn this way, fusion produces neutrons that impact the fissile material layer surrounding the core.
The advantage of this type of technology is Does not require plutonium or uranium isotope U-235 It performs nuclear fission, but you can achieve fission with any uranium isotope. It even works with radioactive waste from nuclear fission reactors.
There is no risk of uncontrolled chain reactions and it produces less radioactive waste than conventional nuclear fission. By the way, there are ways to treat existing waste to make it less hazardous.
The original design dates back to 1977 and, like the tokamak, was the work of Soviet scientists. Of his four techniques mentioned, little experimental development has taken place. So far, one of his few significant breakthroughs has been Kurchatov Institute In Russia, a preliminary design was announced in 2020.
With any luck, we’ll see one of these reactors fully operational within the next decade. Of course, while this artificial sun becomes a reality, we will continue to harness the sun we already have through technologies such as solar cells. Together with wind power, solar power today is the best guarantee of the transition to a more sustainable economy.
sauce: IAEA, ITER, Nature, popular mechanics, power technology, NEI Magazine,
