Mining joke

The fusion reaction of the sun is constrained by gravity, but it still needs huge space to accommodate such a high-temperature object. (Oriental IC/ map)

On May 28th, 20021year, the fully superconducting tokamak nuclear fusion experimental device (EAST), known as the "artificial sun", set a new world record, and successfully realized the repeatable plasma operation of 65438+200 million degrees Celsius10/second and 65438+600 million degrees Celsius for 20 seconds, breaking the record. The researchers said that the new record further proved the feasibility of nuclear fusion energy and laid a physical and engineering foundation for commercialization. This is another successful breakthrough in human control of nuclear fusion.

Nuclear fusion refers to the polymerization of light nuclei, such as hydrogen isotopes deuterium and tritium, into heavier nuclei, such as helium. In the process of fusion, a certain mass will be lost. According to Einstein's equation of mass and energy, these masses will be converted into huge energy. Thermonuclear fusion is a common phenomenon in the universe, and the sun is a huge thermonuclear fusion reactor.

Humans have known about nuclear fusion for almost 100 years. 1932, Mark Oliphant completed the laboratory fusion of hydrogen isotopes. Twenty years later, 1952, the hydrogen bomb test was successful. The hydrogen bomb is the first use of nuclear fusion in human history. However, this method is intense and uncontrollable. In fact, only controllable, human beings can do it, but such a fusion reaction, the input energy is greater than the output energy, not worth the loss, and the time is very short, can not be used to generate electricity. If fusion power generation is to be used, it should not only be controllable, but also output more energy than input, and it should be sustained and stable.

The fusion reaction of the sun is constrained by gravity, but it still needs huge space to accommodate such a high-temperature object. Prominences on the surface of the sun are hundreds of thousands of kilometers higher than the surface of the sun, while the diameter of the earth is only 65438+2000 kilometers. Even so, without the protection of magnetic field and atmosphere, life on earth can't bear the radiation from solar nuclear fusion. Obviously, there is not so much space on the earth. If we want to achieve large-scale integration, we have to think of other ways.

When nuclear fusion occurs, it is in a plasma state, and the temperature reaches tens of millions or even hundreds of millions of degrees. No container can withstand such a high temperature. Then, an idea is to confine the plasma with an invisible force. The way of human thinking is magnetic field.

Since the end of 1940s, many countries have done a lot of research on the feasibility of fusion power generation, invested a lot of manpower and funds, and developed a variety of magnetic cages. 1970s, the "tokamak" invented by Soviet scientists Igor Tamm, Andrei Sakharov and Lev Archie Mouvitz in1950s gradually showed its advantages and became the mainstream of fusion energy research in1980s. The center of tokmak is an annular vacuum surrounded by coils. After electrifying, a huge spiral magnetic field will be generated inside it, which will heat the plasma to a very high temperature and restrain it, so as to achieve the purpose of controlled nuclear fusion.

The Orient in Hefei was built in 2000 and completed in 2006. It was designed and developed by China, also known as the Oriental Super Ring. A series of milestone achievements of EAST show that the research of magnetic confinement fusion in China has begun to lead the international frontier in the physics and engineering of steady-state operation.

However, the technology, capital and manpower required for nuclear fusion are so great that it is often difficult for a country to undertake it alone.

From the late 1970s to the mid-1980s, the United States, Japan, Russia and Europe successively built five large-scale tokamaks. From 65438 to 0985, Reagan-Gorbachev proposed that the Soviet Union, the European Union (through the European Atomic Energy Community), the United States and Japan should participate in the construction of ITER on an equal footing. On May 24th, 2006, a series of relevant cooperation agreements were initialled by representatives of seven countries, namely, the European Union, the United States, China, Japan, South Korea, Russia and India, which marked the start of the plan. ITER is one of the largest and most influential international scientific cooperation projects in the world, and it is also unprecedented in the history of international scientific cooperation. Its construction period is very long, and it is planned to cost 5 billion US dollars (1998 value).

It should be pointed out that ITER's goal is to realize deuterium-tritium discharge self-sustaining for 300-500 seconds, and the expected power is 500MW. But this is still an experiment, and it is still far from commercialization.

Controlled fusion is considered to have brought infinite clean energy to mankind, and long-term planning is very attractive. But unfortunately, in the past few decades, after investing countless funds, the achievements made by scientists are very limited, and the practical commercial value is still out of reach. A long-standing joke among physicists who study fusion: the nuclear fusion technology will enter the practical stage in 30 years, and the news that the nuclear fusion factory is about to start construction will once again be seen in newspapers.

Because the prospects are too bright, it is inevitable that the media will exaggerate.

The industrial history of mankind is nothing more than mining, planting, obtaining raw materials, and then introducing energy to make products. Mining itself needs energy, and planting is nothing more than turning solar energy into carbon compounds. Therefore, human life is essentially determined by the degree of energy utilization. Nuclear fusion can provide cheap and clean energy, and once it is realized, it is bound to fundamentally change our lives.

For example, some industries with high electricity consumption will have no limited electricity and will inevitably change, such as steel and chemical industries. When the cost of electricity is reduced, the cost of the whole product is also reduced. The coal and crude oil industries will be gradually replaced, and the global environment will be better. For another example, electric vehicles are praised as "new energy vehicles" by some people, but some energy sources are not fresh at all, and electricity is still dominated by fossil fuels. Only when controlled nuclear fusion truly occupies the mainstream of energy supply can new energy vehicles with this kind of energy be truly deserved.

The prospect is so beautiful that mankind is eagerly looking forward to it, but the road ahead is long, the road is blocked and difficult, and scientists have yet to explore the endless frontier.

(The author is a researcher at Shanghai Institute of Finance and Law)

(This article only represents the author's personal views and does not represent the position of this newspaper. )

Liu