Nuclear fusion and its large potential for the future world energy supply

An overview of the energy problem in the world is presented. The colossal task of ‘decarbonizing’ the current energy system, with ~85% of the primary energy produced from fossil sources is discussed. There are at the moment only two options that can contribute to a solution: renewable energy (sun, wind, hydro, etc.) or nuclear fission. Their contributions, ~2% for sun and wind, ~6% for hydro and ~5% for fission, will need to be enormously increased in a relatively short time, to meet the targets set by policy makers. The possible role and large potential for fusion to contribute to a solution in the future as a safe, nearly inexhaustible and environmentally compatible energy source is discussed. The principles of magnetic and inertial confinement are outlined, and the two main options for magnetic confinement, tokamak and stellarator, are explained. The status of magnetic fusion is summarized and the next steps in fusion research, ITER and DEMO, briefly presented

High density high performance ELMy H-mode plasmas in the Joint European Tirus (JET)

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Recent progress on JET towards the ITER reference mode of operation at high density

Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H98(y,2) = 1 and densities up to n/nGW ∼ 1 are now routinely obtained. This has been possible (i) by using plasmas at high (δ ∼ 0.5) and medium (δ ∼ 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (δ ∼ 0.5) and low (δ ≤ 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed. © 2001 IOP Publishing Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Toward the realization on JET of an integrated H-mode scenario for ITER

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Exploring New Frontiers of the Ion-Scale Turbulence Suppression by Fast Ions

Understanding and controlling the turbulent transport developing at the ion-scale, which strongly limits the thermal confinement in tokamaks, is crucial in view of the steady-state ITER operations. As ITER will be mainly heated by the fusion-born alpha particles, the development of ITER-relevant scenarios, together with complex numerical analyses, is crucial in order to study the possible effects of the alpha particles on turbulence regimes to date not explored in detail. Therefore, the present work aims at unveiling further steps towards the complete understanding of the impact of fast ions on the microturbulence, by extending the frontiers of our knowledge towards MeV-range of fast ion energy and turbulence patterns different to the well-established ITG, by means of very demanding gyrokinetic numerical analyses.5th Asia Pacific Conference on Plasma Physic

Recent H majority inverted radio frequency heating scheme experiments in JET-ILW

Inverted 3He and D ion cyclotron minority heating scenarios were recently tested in JET-ILW. They confirm the good heating efficiency at low concentrations of ∼3%. The 3He minority heating scheme is only modestly affected by the change from a carbon (JET-C) to a Beryllium (JET-ILW) wall but unlike what was the case in JET-C, the intrinsic Be ions D-like particles in terms of charge-over-mass ratio do not prevent the D (or 4He) minority regime from being exploited. Direct and indirect evidence of the existence of fast particle subpopulations was found in both cases

Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak

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