In an era of technological explosion, new things are generated almost every day, but of all the expected future technologies, the most high-profile is undoubtedly controlled nuclear fusion.
Why is there so much interest in controlled nuclear fusion? Because this is a transformative technology that is different from other technologies, its success will completely change the way we live and will bring human civilization into a new stage of development. Energy is the foundation of the development of civilization, the more advanced civilization, the greater the demand for energy, if the way of obtaining energy can not be changed, civilization will be difficult to continue to develop. Take the fossil energy used by human beings today, which is the key factor restricting human beings to move towards the sea of stars. Fossil energy is so heavy that the payload of a carrier rocket weighing more than 3,000 tons is only about 100 tons, so how can we fly to the sea of stars?
Controlled nuclear fusion is different, it is extremely efficient and very stable, if controlled nuclear fusion can really be achieved, far from it, at least we can sail freely in the solar system, and the spaceship in science fiction movies will become a reality.
Another advantage of controlled nuclear fusion is cleanliness, compared to the pollution generated by fossil fuels, nuclear energy is undoubtedly clean, but the traditional controlled nuclear fission will still produce a certain amount of radioactive waste, and once a nuclear leakage accident may bring significant nuclear pollution to the surrounding area. But controlled nuclear fusion is different in that it reacts stably under natural conditions without generating radioactive waste or the risk of nuclear leakage. Controlled nuclear fusion is so good, what is its principle?
In simple terms, controlled nuclear fusion is to let two light atoms collide in a high-temperature and high-pressure environment and aggregate into a heavy atom, and in the process, there will be a loss of mass, and the lost mass will be released in the form of energy.
From the mass-energy equation, energy is equal to the square of mass multiplied by the speed of light, so some mass loss will turn into huge energy. Specifically, what exactly is the raw material needed for controlled nuclear fusion? Some people say that helium 3, indeed, deuterium and helium 3 can carry out nuclear fusion reactions, and the moon has a very rich helium-3 resources, but the problem is that the technical difficulty of this reaction is relatively high, belongs to the second generation of nuclear fusion, and now we are studying the first generation of nuclear fusion with relatively low technical difficulty, and the raw materials used are the two isotopes of hydrogen, deuterium and tritium.
Are the earth rich in deuterium and tritium?
Deuterium is very rich, we know that the blue planet of the earth is not lacking in seawater, 71% of the surface of the earth is covered by the ocean, and each liter of seawater contains 0.03 grams of deuterium, calculated down, the earth's ocean in the deuterium as much as 40 trillion tons, if only used for controlled nuclear fusion reactions, then it can be said to be inexhaustible. Unlike tritium, tritium on Earth is very rare, because although tritium is an isotope of hydrogen, it is a radioactive element, and the half-life of this radioactive element is very short, only 12.43 years, so even if there is tritium in nature, it will soon decay into other substances, which cannot be preserved for a long time, and there are almost no conditions in nature that can naturally synthesize tritium.
Tritium on Earth is so rare, and controlled nuclear fusion is indispensable, what to do? It can only be synthesized.
In principle, it is not too difficult to synthesize tritium, only need to bombard lithium with neutrons to get, and in reality, if you want to make synthetic tritium, you can use gas-liquid catalytic exchange technology and special electrolysis technology. In fact, synthetic tritium is not difficult, the difficulty lies in consumption and cost. The study of controlled nuclear fusion is to obtain energy, and the process of making tritium necessarily consumes energy, and the later confinement fusion reaction also consumes energy, so can consumption be proportional to output? Although there are many technologies for synthetic manufacturing of tritium, the cost is very high, and it is still difficult to produce in large quantities, which is also a difficulty to face in the process of controlled nuclear fusion research.
In addition to the acquisition of raw materials, there are many difficulties faced by controlled nuclear fusion.
The reason why the sun can emit light and heat is because of the nuclear fusion reaction inside it, so controlled nuclear fusion is also called "small sun". But unlike the Sun, the pressure inside the Sun is high, but the Earth cannot produce such a huge pressure, so to promote the fusion reaction requires a higher temperature, which has far exceeded the melting point of all known materials, so what is used to support the fusion reaction? The current research direction is mainly magnetic field constraints, and it is conceivable that this research path is full of thorns. Some scientists believe that the realization of controlled nuclear fusion is still a hundred years old, and some people are optimistic that it will work in a few years, in fact, as far as the current research progress is concerned, these are just unfounded speculations, and we only hope to see this transformative technology in our lifetime.