Magnetic-confinement fusion

Ongena, J.; Koch, R.; Wolf, R. C.; Zohm, H.

doi:10.1038/nphys3745

Cited by 195 publications

(131 citation statements)

References 77 publications

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“…The insert shows an example of the computed RF electric field pattern in a cross-section of the JET plasma. b, 'Threeion' scenarios require resonant ions with a (Z/A) ratio in between that of the two main ions, essentially following the 'sandwich' principle (Z/A) 2 < (Z/A) 3 < (Z/A) 1 . The figure shows the fraction of RF power absorbed by 3 There is, however, an elegant way to use mixture plasmas to channel RF power to ions: simply add a third ion species with a cyclotron resonance layer close to the IIH cutoff-resonance pair.…”

Section: Figure 1 | a New Technique For Fast-ion Generation In Magnetmentioning

confidence: 99%

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Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

Kazakov¹,

Ongena²,

Wright

et al. 2017

Nature Phys

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We describe a new technique for efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed 'three-ion' scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of this technique on the world-largest plasma magnetic confinement device JET (Joint European Torus, Culham, UK) and the high magnetic field tokamak Alcator C-Mod (MIT, USA). The obtained results demonstrate efficient acceleration of 3 He ions to high energies in dedicated hydrogen-deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3 He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space plasma environments, in particular, 3 He-rich solar flares.Accepted version of the paper published in Nature Physics (2017) http://dx

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Section: Figure 1 | a New Technique For Fast-ion Generation In Magnetmentioning

confidence: 99%

“…A variety of strong wave-particle interactions is possible when the wave frequency is close to the particle's cyclotron frequency or its harmonics [1][2][3] . Ion cyclotron resonance heating (ICRH) is a powerful tool used in toroidal magnetic fusion research.…”

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confidence: 99%

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

Kazakov¹,

Ongena²,

Wright

et al. 2017

Nature Phys

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“…The neutron splits the lithium into tritium and helium. The tritium ( 3 H) is produced by the 6 Li(n, 3 H) 4 He reaction, and is taken out of the blanket and fed into the reactor for maintaining the D-T reaction. The helium is a non-radioactive, non-toxic and valuable exhaust product.…”

Section: Tritium Self-sufficiency (Mission 4)mentioning

confidence: 99%

“…Of the various approaches to generate fusion electricity, magnetic confinement fusion [4] is the furthest advanced. At the high temperatures required for fusion on Earth (≈ 10-15 keV), all matter is fully ionised and in the plasma state.…”

Section: Introductionmentioning

confidence: 99%

Scientific and technical challenges on the road towards fusion electricity

Donné¹,

Federici²,

Litaudon³

et al. 2017

J. Inst.

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A: The goal of the European Fusion Roadmap is to deliver fusion electricity to the grid early in the second half of this century. It breaks the quest for fusion energy into eight missions, and for each of them it describes a research and development programme to address all the open technical gaps in physics and technology and estimates the required resources. It points out the needs to intensify industrial involvement and to seek all opportunities for collaboration outside Europe. The roadmap covers three periods: the short term, which runs parallel to the European Research Framework Programme Horizon 2020, the medium term and the long term.ITER is the key facility of the roadmap as it is expected to achieve most of the important milestones on the path to fusion power. Thus, the vast majority of present resources are dedicated to ITER and its accompanying experiments. The medium term is focussed on taking ITER into operation and bringing it to full power, as well as on preparing the construction of a demonstration power plant DEMO, which will for the first time demonstrate fusion electricity to the grid around the middle of this century. Building and operating DEMO is the subject of the last roadmap phase: the long term. Clearly, the Fusion Roadmap is tightly connected to the ITER schedule. Three key milestones are the first operation of ITER, the start of the DT operation in ITER and reaching the full performance at which the thermal fusion power is 10 times the power put in to the plasma. The Engineering Design Activity of DEMO needs to start a few years after the first ITER plasma, while the start of the construction phase will be a few years after ITER reaches full performance. In this way ITER can give viable input to the design and development of DEMO. Because the neutron fluence in DEMO will be much higher than in ITER, it is important to develop and validate materials that can handle these very high neutron loads. For the testing of the materials, a dedicated 14 MeV neutron source is needed. This DEMO Oriented Neutron Source (DONES) is therefore an important facility to support the fusion roadmap. K: Nuclear instruments and methods for hot plasma diagnostics; Instrumentation for neutron sources

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“…1. ) A statistical treatment leads to the kinetic model, based on the Vlasov equation (equation (1)), essentially Liouville's theorem applied to the specific plasma environment, with interactions that are dominated by electromagnetic fields and a separation between particle collisions -that is, interactions at microscopic scales-and long-range fields. The Vlasov equation describes the evolution of f s (x,v,t), the single-particle phase-space distribution function of the species labelled 's' (electrons or ions), under the e ect of the longrange electric and magnetic fields E and B, which evolve according to Maxwell's equations with plasma charge and current densities as sources: Here, x, v, q s and m s stand for the position, velocity, charge and the mass of a particle of species 's' , respectively.…”

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confidence: 99%

Computational challenges in magnetic-confinement fusion physics

et al. 2016

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Magnetic-fusion plasmas are complex self-organized systems with an extremely wide range of spatial and temporal scales, from the electron-orbit scales (⇠10 11 s, ⇠10 5 m) to the di usion time of electrical current through the plasma (⇠10 2 s) and the distance along the magnetic field between two solid surfaces in the region that determines the plasma-wall interactions (⇠100 m). The description of the individual phenomena and of the nonlinear coupling between them involves a hierarchy of models, which, when applied to realistic configurations, require the most advanced numerical techniques and algorithms and the use of state-of-the-art high-performance computers. The common thread of such models resides in the fact that the plasma components are at the same time sources of electromagnetic fields, via the charge and current densities that they generate, and subject to the action of electromagnetic fields. This leads to a wide variety of plasma modes of oscillations that resonate with the particle or fluid motion and makes the plasma dynamics much richer than that of conventional, neutral fluids.T he most straightforward way for describing plasmas would be the microscopic particle approach: solving the equations of motion for the many individual particles that form the plasma in externally imposed electromagnetic fields and in the fields that the particles themselves generate. However, this is computationally impossible to apply to realistic magnetic-fusion plasmas, which typically contain 10 22 -10 23 particles. (For a review of the basic concepts of magnetically confined fusion plasmas, see ref. 1.)A statistical treatment leads to the kinetic model, based on the Vlasov equation (equation (1)), essentially Liouville's theorem applied to the specific plasma environment, with interactions that are dominated by electromagnetic fields and a separation between particle collisions -that is, interactions at microscopic scales-and long-range fields. The Vlasov equation describes the evolution of f s (x,v,t), the single-particle phase-space distribution function of the species labelled 's' (electrons or ions), under the e ect of the longrange electric and magnetic fields E and B, which evolve according to Maxwell's equations with plasma charge and current densities as sources:Here, x, v, q s and m s stand for the position, velocity, charge and the mass of a particle of species 's' , respectively. In the Vlasov model, collisions are neglected, an approximation that is generally justified for fusion plasmas because small-scale e ects based on Coulomb interactions become very weak at high temperatures. In fact, Coulomb collisions' cross-sections for the exchange of momentum and energy, and related quantities such as the electrical resistivity ⌘, scale with T 3/2 . In ITER core plasmas (see ref. 1), for example, T ⇡ 10 keV (⇡10 8 K) and the electron-electron ('ee'), electron-ion ('ei') and ion-ion ('ii') collisional exchanges of momentum and energy ('E') occur over relatively long characteristic times:2)-justifying the collisi...

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Magnetic-confinement fusion

Cited by 195 publications

References 77 publications

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

Scientific and technical challenges on the road towards fusion electricity

Computational challenges in magnetic-confinement fusion physics

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