Progress in stellarator/heliotron research: 1981–1986

Carreras, B. A.; Grieger, G.; Harris, J. H.; Johnson, John L.; Lyon, J. F.; Motojima, O.; Rau, F.; Renner, H.; Rome, J.A.; Uo, K.; Wakatani, Masahiro; Wobig, H.

doi:10.1088/0029-5515/28/9/011

Cited by 83 publications

(40 citation statements)

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“…Both the beta gradient and the Reynolds number are the key parameters in the GMT models shown in Eq. (2). The magnetic Reynolds number in the A p ¼ 8.3 configuration discharges are much lower by one order than that in A p ¼ 6.2 for the same beta value.…”

Section: -6mentioning

confidence: 79%

“…The Large Helical Device (LHD) 1 is a heliotron device, 2 which is a helical type toroidal magnetic plasma confinement system and a probable candidate as the thermonuclear fusion reactor under the steady-state operation because it can confine plasma with only external coils. The heliotron device is characterized as the relatively week magnetic shear and hill (sometimes magnetic well) in the core and the relatively strong shear and hill in the periphery.…”

Section: Introductionmentioning

confidence: 99%

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Effect of pressure-driven MHD instabilities on confinement in reactor-relevant high-beta helical plasmas

et al. 2011

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Through the experiment data analysis in the large helical device (LHD), the influence of the global MHD instability and the relatively short wave length MHD instabilities driven turbulence on the confinement performance in reactor-relevant high-beta helical plasmas is studied. The comparison of the energy confinement time between just before global MHD instability disappears and after that, and the estimation of the saturated mode structure by the multi-channel soft x-ray measurement enable us to quantitatively estimate the influence of the global interchange type MHD instability with different saturated mode structures on the confinement performance. According to the comparison between thermal conductivities in experiments and those predicted by theoretical transport models, the transport properties in the peripheral region of high beta LHD plasmas are quite similar with anomalous transport model based on an interchange type MHD instability driven turbulence, and that result is supported by the dependence of the density fluctuation with relatively short wave length on beta value.

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Section: -6mentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Effect of pressure-driven MHD instabilities on confinement in reactor-relevant high-beta helical plasmas

et al. 2011

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“…For these conditions, additional non-local convective transport contributions [31] can further degrade confinement. It should be mentioned in this context, that the original goal of TJ-II was MHD-stability investigations at high β [32] and not neoclassical confinement in the lmfp-regime. Due to the highῑ (ῑ ≃ 3/2 for the "standard" configuration considered in this benchmarking) the Shafranov shift is rather small and β-effects on the neoclassical confinement are less important.…”

Section: B the Magnetic Configurationsmentioning

confidence: 99%

Neoclassical transport simulations for stellarators

et al. 2011

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The benchmarking of the thermal neoclassical transport coefficients is described using examples of the Large Helical Device (LHD) and TJ-II stellarators. The thermal coefficients are evaluated by energy convolution of the mono-energetic coefficients obtained by direct interpolation or neural network techniques from databases precalculated by different codes. The temperature profiles are calculated by a predictive transport code from the energy balance equations with the ambipolar radial electric field estimated from a diffusion equation to guarantee a unique and smooth solution although several solutions of the ambipolarity condition may exist when root-finding is invoked; the density profiles are fixed. The thermal transport coefficients as well as the ambipolar radial electric field are compared and very reasonable agreement is found for both configurations.Together with an additional W7-X case, these configurations represent very different degrees of neoclassical confinement at low collisionalities. The impact of the neoclassical optimization on the energy confinement time is evaluated and the confinement times for different devices predicted by transport modeling are compared with the standard scaling for stellarators. Finally, all configurations are scaled to the same volume for a direct comparison of the volume-averaged pressure and the neoclassical degree of optimization.

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“…El propio diseño y la construcción de un Stellarator es una tarea difícil y constituyen en sí mismas un reto tecnológico (Carreras, 1988), puesto que pequeños errores en el cálculo o la fabricación de las bobinas externas pueden suponer errores de campo magnético importantes (Figura 6); quizá sea esta una de las razones por la que esta línea de confinamiento tardó más en desarrollarse y de que actualmente esté más avanzado el modelo Tokamak, siendo en este tipo de máquinas donde se han conseguido mejores resultados en cuanto a parámetros globales del plasma como densidad, temperatura o tiempos de confinamiento. La geometría de los Stellarators es más compleja que la de los Tokamaks, no teniendo en general simetría respecto al eje, por lo que tanto la componente toroidal como la poloidal del campo magnético dependen de la posición y varían poloidalmente.…”

Section: Dispositivos Stellaratorunclassified

La ingeniería nuclear y el desarrollo de mecanismos de fusión por confinamiento magnético

Obaldía

2014

Ingeniería

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ResumenLa fusión nuclear es el proceso mediante el cual los núcleos ligeros se unen para formar núcleos más pesados, y es el proceso que genera la energía del sol y las estrellas (estas reacciones de fusión se producen a temperaturas del orden de los 150 millones de grados Celsius). Densidades del orden de 10 20 m -3 y temperaturas iónicas en torno a 10 keV son características claves que garantizan un estado estable de ionización de la materia llamado "plasma". El proceso de fusión más accesible experimentalmente es aquel en que reaccionan núcleos de deuterio y tritio generando una partícula alfa y un neutrón. De la energía cinética generada en la fusión de los núcleos de deuterio y tritio, el 80% reside en las partículas neutras (neutrones) mientras que el 20% restante lo hace en los núcleos de He (partículas α). La espectroscopia visible, la dispersión Thomson, la interferometría de microondas, las sondas de iones pesados, y las sondas de Langmuir, son algunos de los sistemas de diagnóstico utilizados para caracterizar la materia en este estado. El reto de la fusión es reproducir en la Tierra las reacciones que se producen en el interior de las estrellas; por lo tanto la densidad en un dispositivo de fusión nuclear experimental deberá ser de 15 órdenes de magnitud superior a la presente en el gas interestelar y alrededor de 15 órdenes de magnitud inferior al que se encuentra en el interior de algunas estrellas. Estas características técnicas deben reunirse en un reactor capaz de satisfacer una parte sustancial de las necesidades energéticas del planeta a corto plazo.Palabras claves: fusión nuclear, Stellarator, Tokamak, átomo, plasma, espectroscopia, interferometría, iones pesados, sondas de Langmuir AbstractNuclear fusion is the process by which light nuclei combine to form heavier nuclei, and is the process that generates energy from the sun and stars (these fusion reactions occur at temperatures of the order of 150 million Celsius). Densities of the order of 10 20 m -3 and ion temperatures of about 10 keV are key features which ensure a stable state of ionization of matter called "plasma". The fusion process is one in experimentally accessible reactive deuterium and tritium nuclei generating an alpha particle and neutron. From the kinetic energy generated in the fusion of deuterium and tritium nuclei, 80% reside in neutral particles (neutrons) while 20% use in the nuclei of He (α particles). Visible spectroscopy, Thomson scattering, Interferometry microwave, Probes heavy ions, and Langmuir probes are some diagnostic systems used to characterize the material in this state. The challenge of the fusion is duplicated on Earth reactions occurring inside the star; therefore density in experimental nuclear fusion devices must be 15 orders of magnitude higher than the gas present in the interstellar and about 15 orders of magnitude lower than that found in the interior of some stars. These specifications should meet in a reactor capable of meeting a substantial portion of the world's energy needs in the short term.

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Progress in stellarator/heliotron research: 1981–1986

Cited by 83 publications

References 0 publications

Effect of pressure-driven MHD instabilities on confinement in reactor-relevant high-beta helical plasmas

Effect of pressure-driven MHD instabilities on confinement in reactor-relevant high-beta helical plasmas

Neoclassical transport simulations for stellarators

La ingeniería nuclear y el desarrollo de mecanismos de fusión por confinamiento magnético

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