Shulou(Shulou.com)11/24 Report--

Beijing, December 14 (Xinhua)-- US scientists have achieved net energy gain in nuclear fusion for the first time, the US Department of Energy confirmed at a press conference on Tuesday. The breakthrough suggests that nuclear fusion may eventually provide a rich, zero-carbon alternative to fossil fuels.

"this is a landmark achievement," US Energy Secretary Jennifer Glenhom (Jennifer Granholm) said at a press conference on Tuesday. "We have taken a tentative first step towards a clean energy that could revolutionize the world," said Jill Hruby, director of the National Nuclear Safety Administration.

But how much does this breakthrough bring the energy sector closer to realizing the dream of nuclear fusion energy?

What is nuclear fusion? Nuclear fusion is a reaction that provides energy for the sun. This process involves heating two hydrogen isotopes, usually deuterium and tritium, to extreme temperatures, resulting in nuclear fusion, releasing helium and large amounts of energy in the form of neutrons.

Unlike nuclear fission, this process does not produce long-standing radioactive waste and does not emit carbon. Scientists estimate that a small cup of this fuel can power a house for more than 800 years. Proponents of fusion technology describe it as the "holy grail" of clean energy, a technology that can theoretically provide almost unlimited, zero-carbon energy.

Lawrence Livermore National Laboratory, however, although Soviet scientists developed the first nuclear fusion machine in the 1950s using a technology called "magnetic confinement", before Tuesday, no research team has been able to generate more energy in the fusion reaction than it consumes, a process known as scientific energy gain or target gain and is seen as a scientific milestone in the field.

What has the United States done? Scientists at the National Ignition Facility (NIF) at the U.S. Department of Energy's Lawrence Livermore National Laboratory (LLNL) have achieved the goal of energy gain in nuclear fusion for the first time.

NIF, which cost $3.5 billion, was launched in 2009, initially to test nuclear weapons by simulated explosions, and then to advance fusion energy research.

At present, magnetic confinement is still the most widely studied method of nuclear fusion, which uses huge magnets to hold deuterium-tritium fuel in place and heat it to a higher temperature than the sun.

However, NIF uses a different technique called inertial confinement. It uses 192 lasers to burn a miniature fuel capsule (fuel capsule). The laser heated the fuel to more than 3 million degrees Celsius, causing the surface of the target capsule to burn and explode, causing what NIF described as a "rocket-like" implosion. This compresses and further heats the fuel until the hydrogen atoms in deuterium and tritium fuse, releasing helium and energy.

The process of inertial confinement fusion in the nuclear fusion experiment on December 5, 2022, NIF injected 2.05 megajoules of energy into the target, resulting in a fusion energy output of 3.15 megajoules, with an energy gain of 153%, exceeding the preliminary results of 120% energy gain previously reported by the media.

Have humans conquered nuclear fusion energy? No, not yet. For decades, the realization of energy gain has been seen as a key step in proving the feasibility of commercial nuclear substations. However, it still has several obstacles to overcome.

First of all, the energy gain in the experiment only compares the generated energy with the energy in the laser, not with the total energy extracted from the power grid to power the system. In fact, each launch requires 330 megajoules of electricity, transmitted in the form of 400 microsecond pulses.

Moreover, the system that NIF powers lasers is very old and is not designed for maximum energy efficiency. However, scientists still estimate that commercial nuclear fusion will require a fusion reaction of 30 to 100 times the input energy. NIF can only be launched once a day at most, while a power plant that uses inertial confinement fusion technology may need to complete several launches a second.

"this experiment clearly proves that the physics of laser fusion is effective," said Robbie Scott, a plasma physicist who contributed to NIF research. "the next step will include demonstrating higher fusion energy gains and further developing more efficient ways to drive implosions."

Compared with the recent breakthroughs of other countries? NIF's achievement follows the announcement of significant results by other publicly funded fusion laboratories over the past 18 months, albeit with slightly different research objectives.

In the early morning of May 28, 2021, the fully superconducting tokamak Nuclear Fusion Experimental Facility (EAST) of the Hefei Institute of material Sciences of the Chinese Academy of Sciences set a new world record, successfully achieving a repeatable plasma operation of 120 million degrees Celsius for 101 seconds and 160 million degrees Celsius for 20 seconds, Xinhua reported. This extends the previous record of 100 million degrees Celsius for 20 seconds by five times, and represents an important step towards the use of nuclear fusion energy. EAST, also known as China's "artificial sun", is a magnetically confined nuclear fusion experimental device independently developed by the Institute of Plasma Physics, Hefei Institute of material Sciences, Chinese Academy of Sciences.

EAST is known as China's "artificial sun". In December last year, researchers at the European United Ring reactor (JET), the world's largest and most powerful tokamak nuclear reactor in Oxford, generated a record 59 megajoules of energy during a five-second fusion reaction. That's enough to boil about 60 kettles, more than double the energy output record of 22 megajoules set by JET in 1997.

Experts pointed out that neither of these two nuclear fusion reactions achieved energy gain as NIF did, but neither of them gave priority to achieving energy gain in experiments.

Accelerate industry research for the energy sector, they hope that this breakthrough will stimulate interest and investment, thereby accelerating the progress of nuclear fusion energy.

Historically, most fusion science has been done by publicly funded laboratories such as NIF and JET, but in recent years investment has also poured into private companies that promised to provide fusion energy in the 1930s.

Plasma physicist Melanie Wendridge (Melanie Windridge) runs Fusion Energy Insights, a fusion energy consulting firm. She points out that NIF, which cost $3.5 billion to build, is 13 years old and is based on laser technology developed in the 1980s.

"if you can do this with old technology, it shows the possibility of the latest equipment. If they have private support and can move forward on these radical schedules, then they can use cutting-edge technology. This is very exciting." Wendridge said.

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