- 3437 - NUCLEAR FUSION - closer to a power source? Nuclear fusion has long seemed futuristic and unattainable. Now, this future is finally coming into focus a new report from the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory.
------------- 3437 - NUCLEAR FUSION - closer to a power source?
- Nuclear scientists from NIF have proven through four experiments that it is possible to achieve burning plasma which is a crucial milestone along the journey to full nuclear fusion. This brings nuclear physics one step closer to recreating the kind of sustained nuclear fusion that burns inside the heart of a star, and our Sun.
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- The physical conditions required to generate a burning plasma are extreme, and it requires very precise control to make it happen, enabling the potential for rapidly increasing fusion performance.
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- When you think of nuclear energy, it probably brings to mind images of conical smoke stakes. But, this kind of nuclear energy is “fission.” , not “fusion”. Fission happens when atomic nuclei, the center of atoms, are broken apart to release energy bursts that create electricity by powering steam.
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- Nuclear fission is a greener alternative to oil and coal, but it has often faced criticism over mismanagement of aging facilities like the Chernobyl meltdown and the toxic waste it leaves behind. Fission takes heavy nuclei and breaks them into smaller nuclei releasing energy.
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- On the other hand, nuclear fusion is much cleaner. By smashing light nuclei together to create one heavy one (example: two hydrogen atoms creating one helium atom), nuclear fusion could create clean, self-sustaining, and waste-free energy.
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- In a world of clean energy sources that struggle to generate power on cloudy or still days, an autonomous energy source could be huge. However nuclear fusion is not only incredibly difficult to do but even measuring crucial milestones, like burning plasma, presents a challenge.
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- For fusion plasma to be able to produce more energy than was used to create it… it must first be able to heat itself (‘self-heating’) by retaining some of the energy generated during fusion. The threshold at which the fusion plasma self-heating just exceeds the external sources of heating applied to make it is what we call a ‘burning plasma’.
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- A burning plasma has no obvious data signature, so we use data inferences to understand if the energy balance in our plasma has shifted into a burning state or not. This uncertainty can mean that making the call of whether or not their experiments have really achieved burning plasma difficult.
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- Achieving burning plasma doesn’t mean that fusion energy is coming to our homes anytime soon, but it does represent a big step toward this goal. The dream of fusion is that it can provide a carbon-free, safe, and reliable source of energy. Creating a burning plasma is a clear milestone on the way towards demonstrating energy production from fusion that would be relevant for power production.
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- Here’s what the team did:
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--------------------------- A spherical capsule of deuterium-tritium fuel (which can be created in part from seawater) is placed in a hollow container called a hohlraum
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-------------------------- In a process “indirect drive inertial confinement” fusion, 192 lasers are pointed at the hohlraum to generate x-rays
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------------------------- These x-rays heat the fuel capsule and hohlraum such that the fuel capsule compresses thousands of times its original volume in only a fraction of a second
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------------------------- By measuring the energy balance in the plasma, they were able to determine an energy yield of up to 170 kilojoules of energy.
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- While this doesn’t yet surpass the amount of energy put into generating the reaction, it was many times greater than previous experiments. The results in this are evidence that self-sustaining nuclear fusion is no longer a thing of science fiction.
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- Obtaining a burning plasma is a critical step towards self-sustaining fusion energy. A burning plasma is one in which the fusion reactions themselves are the primary source of heating in the plasma, which is necessary to sustain and propagate the burn, enabling high energy gain.
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- After decades of fusion research they are achieving a burning-plasma state in the laboratory. These experiments were conducted at the US National Ignition Facility, a laser facility delivering up to 1.9 megajoules of energy in pulses with peak powers up to 500 terawatts.
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- They use the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule via the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work.
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- The burning-plasma state was created using a strategy to increase the spatial scale of the capsule through two different implosion concepts.
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- These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics. A subset of experiments appear to have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction.
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- These results provide an opportunity to study “particle-dominated plasmas” and “burning-plasma physics” in the laboratory. When will fusion generated electricity get to you home?
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January 28, 2022 NUCLEAR FUSION - closer to a power source? 3422
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----------------------------- Friday, January 28, 2022 ---------------------------
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