- 3550 - NUCLEAR FUSION - to generate electric power? To break free from our dependence on fossil fuel we need nuclear fusion power generation which has long seemed futuristic and unattainable. Now, this future is finally coming into sharp relief in light of a new report from the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory.
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-------------- 3550 - NUCLEAR FUSION - to generate electric power?
- 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.
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- These experiments at NIF are a technical triumph that brings nuclear physics one step closer to recreating the kind of sustained nuclear fusion the same that burns inside the heart of a star.
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- The burning plasma threshold is the physical conditions required to generate a burning plasma. This extreme condition requires very precise control to enabling rapidly increasing fusion performance.
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- Nuclear bombs are ‘fission’ explosions that take a heavy elements like Uranium that breaks them apart to release energy. Nuclear fusion is the opposite. Fusion takes lighter elements like hydrogen and helium combines them together to release energy without radioactivity.
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- Nuclear “fission.” happens when the atomic nuclei, the center of atoms, are broken apart releasing energy bursts that create heat that gets electricity by powering steam. While nuclear fission is a greener alternative to oil and coal, it has often faced criticism over mismanagement of aging facilities (think the Chernobyl meltdown) and the toxic waste it leaves behind.
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- On the other hand, nuclear “fusion” has a much cleaner process. By smashing light nuclei together to create one heavy one (two hydrogen atoms creating one helium atom), nuclear fusion could create clean, self-sustaining, and waste-free energy.
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- Nuclear fusion is not only incredibly difficult to do but even measuring crucial milestones, like burning plasma, presents an incredible 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 signature, so we use data inferences to understand if the energy balance in the 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 is 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. This work will bring fusion research even closer to its goal of clean, self-sustaining energy.
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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. The process is called “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. By measuring the energy balance in the plasma, scientists are able to determine an energy yield of up to 170 kilojoules of energy. While this doesn’t yet surpass the amount of energy put into generating the reaction, it was many times greater than previous experiments.
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- More recent results have already been surpassed this August, 2021 by another experiment of the same type at NIF. The results in this experiment 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 scientists have finallynachieved 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 used the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule using the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work.
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- The capsule used two different implosion concepts. These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics.
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- These experiments have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction. These results provide an opportunity to study α-particle-dominated plasmas and burning-plasma physics in the laboratory.
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- These is only one necessary step on the way to nuclear fusion generation of electric power.
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April 20, 2022 NUCLEAR FUSION - to generate electric power? 3550
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