Controlled nuclear fusion energy: How far is humanity from achieving energy freedom?

On the afternoon of August 25, China National Nuclear Corporation released an official announcement that the new generation of artificial sun "China Toroidal 3" has made major scientific research progress, and for the first time achieved high confinement mode operation under a plasma current of 1 million amperes, once again breaking the operation record of my country's magnetic confinement fusion device, and breaking through key technical difficulties such as plasma high current high confinement mode operation control, high-power heating system injection coupling, and advanced divertor position control. This marks that my country's magnetic confinement nuclear fusion research has taken an important step towards high-performance fusion plasma operation.

Steady-state operation of magnetic confinement fusion can achieve steady-state energy output

All things grow with the help of the sun. The reason why the sun shines and emits heat is because of the nuclear fusion reaction inside it. The raw materials for nuclear fusion are extremely abundant on the earth. If we can build a "sun" to generate electricity, humans will hopefully achieve energy freedom. The artificial sun has a similar operating mechanism to the sun and can use nuclear fusion reactions to generate huge amounts of energy.

Controlled nuclear fusion has outstanding advantages such as abundant resources, environmental friendliness, and inherent safety. It is one of the important ways currently recognized to ultimately solve mankind's energy problems.

"China Tonliu-3" was independently designed and built by the Southwest Institute of Physics of the China National Nuclear Corporation. Xiao Guoliang, an associate researcher at the Southwest Institute of Physics of the China National Nuclear Corporation, said that there are three main types of controlled nuclear fusion based on the confinement method, namely gravitational confinement fusion with the sun as an example, inertial confinement fusion represented by laser fusion, and magnetic confinement fusion represented by the tokamak device.

Magnetic confinement fusion is a technology that uses magnetic fields to confine plasma in fusion fuel in space. The Tokamak device is the mainstream device for controlled nuclear fusion research. It uses a strong magnetic field to control plasma at hundreds of millions of degrees Celsius in a vacuum container for a long time, and allows the fusion reaction to proceed stably and continuously.

"The high confinement mode (H mode) in magnetic confinement nuclear fusion is a typical advanced operating mode and has been selected as the standard operating mode of the International Thermonuclear Experimental Reactor (ITER) under construction." Xiao Guoliang said that this method will be able to achieve stable energy output through steady-state operation in the future, and it is also the most promising way to realize the utilization of fusion energy first.

Artificial sun achieves ultra-large current and high-confinement operation

There are three parameters to measure the level of nuclear fusion devices and nuclear fusion research: fuel ion temperature, plasma density and energy confinement time. Only when the product of the three parameters exceeds a certain value can true nuclear fusion be achieved. Future fusion reactor devices will usually operate stably at more than 1 million amperes to achieve higher fusion parameters and output energy.

In order to realize the utilization of fusion energy, it is necessary to improve the comprehensive parameters of plasma to the fusion ignition conditions, that is, to achieve the experimental output energy exceeding the input energy. Xiao Guoliang introduced that compared with the ordinary operation mode, the high confinement mode (H mode) in magnetic confinement nuclear fusion can increase the comprehensive parameters of plasma several times, effectively improving the overall confinement performance of plasma.

"The high confinement operation of a plasma current of 1 million amperes can be understood as the high confinement mode being able to better capture the plasma of a current of 1 million amperes for reaction in the magnetic field, thereby obtaining higher fusion plasma parameters." Xiao Guoliang introduced that this is a manifestation of the comprehensive capabilities of a fusion device, including plasma configuration control capability, high-power heating capability, device wall treatment technology, device feeding technology, instability control technology, and advanced diagnostic measurement technology, among other technical breakthroughs.

It is understood that nuclear fusion energy is expected to be commercialized in the middle of this century. Xiao Guoliang said that the "China Toroidal 3" team will further develop core technologies such as high-power heating and current drive, advanced plasma operation control, etc., to achieve core-level plasma operation and accelerate the development of fusion energy.