The world's largest laser 'burns' hydrogen plasma, breaking fusion records

 

The experiment spewed ten quadrillion watts of electricity in an instant.

 

According to researchers, a "self-heating"—or "burning"—plasma of neutron-heavy hydrogen inside the fuel capsule used in the experiment was the key to the record-breaking nuclear fusion experiment that spewed out ten quadrillion watts of electricity in a split second.

 

According to a Live Science article from the time, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in Northern California released 1.3 megajoules of energy for 100 trillionths of a second last year. Two new studies by NIF researchers demonstrate that the success of this fusion experiment was made possible by the meticulous design of the tiny chamber and fuel capsule at the heart of the world's most powerful laser system.

 

The researchers reported that the output of the fuel capsule, which was only around a millimetre (0.04 inch) in diameter, was equivalent to about 10% of all the energy from sunlight that reaches Earth every instant.

 

Researchers claim that the reaction could blast out that much energy because the fusion process turned the remaining fuel into a plasma hot enough to support subsequent fusion events.

 

Annie Kritcher, a physicist at the Lawrence Livermore National Laboratory (LLNL), explained in an email to Live Science that "a blazing plasma is when heating from the fusion processes becomes the major source of heating in the plasma, more than required to commence or jump-start the fusion." Kritcher is the lead author of a study that was published in Nature Physics on January 26 describing how the NIF was optimised to achieve the burning plasma, and he is a co-author of another study that was published in Nature on the same day and describes the first burning plasma experiments at the NIF in 2020 and early 2021.

 

Jarred star

 

The sun and other stars get their energy from a process called nuclear fusion. Nuclear fission, in which heavy atomic nuclei like plutonium are broken into smaller atomic nuclei to create energy, is employed in power plants on Earth.

 

When smaller atomic nuclei are combined to form larger ones, a process known as nuclear fusion occurs, releasing huge amounts of energy.

 

Hydrogen fuels the simplest sorts of fusion. Scientists believe that nuclear fusion can one day be turned into a comparatively "clean" power source using the abundant hydrogen in Earth's oceans.

 

Stars' immense mass and gravity cause the fusion reactions to occur at extremely high pressures. However, such pressures are not achievable on Earth, so fusion processes must instead occur at extremely high temperatures. According to Gay-law and Lussac, the pressure of a gas in a certain container rises as its temperature rises for that container.

 

The National Ignition Facility is an expert in a technique termed "inertial confinement" for keeping a fusion reaction at high temperatures, one of several approaches proposed by experimenters. It uses 192 high-powered lasers, which are extremely energy-intensive and can only be fired once every day or so to hit a tiny particle of hydrogen at the core, generating extremely high temperatures.

 

The inertial confinement method was developed for the purpose of testing thermonuclear weapons, and it is extremely unlikely to ever become a practical power source due to the fact that it would require the vaporisation of multiple fuel pellets per second in order to produce even negligible amounts of electricity.

 

However, the NIF has lately demonstrated success in reaching extremely high energy outputs, albeit for extremely brief periods of time. Researchers anticipate that future trials will be even more potent than the one conducted in August, which nearly extracted as much energy from the fuel pellet as was put into it.

 

Collision with inertia

 

According to the two new studies, experiments with burning plasma were conducted months before the ten quadrillion watt reaction, and their culmination was the production of 170 kilojoules of energy from a pellet of just 200 micrograms (0.000007 ounces) of hydrogen fuel, which is roughly three times the energy output of any previous experiments.

 

The fuel capsule, a tiny spherical shell of polycarbonate diamond that encased the pellet, and the cavity, a tiny cylinder of depleted (not particularly radioactive) uranium lined with gold, known as a hohlraum, were both precisely shaped to accomplish this.

 

The fuel pellet "imploded" at such a high degree that it heated other parts of the pellet into a plasma, and the novel designs allowed the NIF lasers that heated the pellet to operate more efficiently within the hohlraum, causing the hot shell of the capsule to expand outward rapidly.

 

"To produce enormous amounts of energy from fusion relative to the energy we put in, this is a crucial first step," physicist Alex Zylstra told Live Science in an email. Zylstra is the primary author of the Nature publication detailing the first burning plasma experiments.

 

To use inertial confinement fusion as a power source, he said that many more scientific milestones are required, but generating a "burning" plasma will allow scientists to learn more about the process.

 

Burning plasmas at NIF, according to Zylstra, have entered a new phase that allows for rigorous scientific research.

 

According to Kritcher, the advancement will lead to a deeper understanding of nuclear fusion that can be applied to various types of fusion reactions, such as those that occur in tokamaks and those that occur in inertial confinement devices.

 

"This work is significant because it opens the door to a new regime of plasma physics that will yield a wealth of insight for the entire fusion community," she added.

Reference : https://www.livescience.com/burning-hydrogen-plasma-record-breaking-fusion-experiment

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