Direct losses of fast particles in multiple-toroidicity stellarators

Smirnova, M. S.

doi:10.1063/1.1400793

Cited by 3 publications

(6 citation statements)

References 33 publications

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“…It follows from the publications on numerical studies that the confinement of EPs in stellarators is in general a serious problem [113,114] that has not been the focus of transport optimization studies to date. Tangential injection is considered to be the best way to minimize ripple losses in the present day machines.…”

Section: Drift Motion and Tf Ripples In Different Confinement Geometriesmentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

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The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium-tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the 'sea' of Alfvén eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

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Section: Drift Motion and Tf Ripples In Different Confinement Geometriesmentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

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“…The trapping of particles in the third-order wells (figure 10) enhances the fraction of transitional orbits in phase space, causing a predominance of such orbits in the loss cone. As has been shown in the [24], more than 78% of the 10 keV protons that escape in W7-AS3Z2 have transitional orbits.…”

Section: The Case Of the W7-as Modular Stellaratormentioning

confidence: 52%

“…This limitation urges us to develop new methods for investigating charged particle motion and confinement in current multiple helicity and multiple toroidicity stellarator configurations. Unfortunately, a number of methods, developed in earlier studies [18,[20][21][22][23][24] and suitable for solving the abovementioned problems, are not applicable to all types of multiple toroidicity configurations owing to the considerable complexity of their magnetic field geometry. The main goal of this paper is an investigation of the ripple well structure of current stellarator or heliotron configurations, which is accompanied, in contrast to the classical heliotron configuration, by a variety of such additional ripples.…”

Section: (E))mentioning

confidence: 99%

The behaviour of magnetic ripple wells along field lines in current heliotrons and stellarators: comparison with a classical heliotron

Smirnova¹

2003

Plasma Phys. Control. Fusion

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For the stellarator-type devices of today, which are very different from the quasi-symmetric ones, the analytical conditions for the existence of two kinds of ripple wells along field lines are derived taking into account the multiple helicity and multiple toroidicity of the magnetic field. It is shown that a typical feature of the above-mentioned devices, in contrast to a classical heliotron, is a considerable deformation of magnetic wells, both ordinary and secondary, by additional ripple fields. When this deformation exceeds a critical level, one kind of magnetic ripple well can be suppressed in some toroidal region. This happens if the amplitudes of the helical and toroidal magnetic fields and the amplitudes of the ripple fields are correlated with each other through the relations known as conditions for parametric resonance. When the parametric resonance conditions are fulfilled, charged particle confinement is improved because of a suppression of the toroidal drift.

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“…10 that the particle losses follow roughly the same scaling because higher kicks to the particles' perpendicular velocity increase inevitably the radial drift, see eq. (7). Distribution functions of confined particles resulting from the scan in P RF is shown in Fig.…”

Section: Guiding Centre Simulations Including a Radial Electric Fieldmentioning

confidence: 99%

“…Fast particle losses due to more exotic orbits, e.g. stochastic trapped orbits, were thoroughly studied in [6,7]. The confinement of fast ions in various W7-X configurations were published in [8].…”

Section: Introductionmentioning

confidence: 99%

ICRH induced particle losses in Wendelstein 7-X

Faustin

Cooper

Graves

et al. 2016

Plasma Phys. Control. Fusion

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Fast ions in W7-X will be produced either by Neutral Beam Injection (NBI) or by Ion Cyclotron Resonant Heating (ICRH). The latter presents the advantage of depositing power locally and does not suffer from core accessibility issues [M. Drevlak et al Nucl. Fusion 2014]. This work assesses the possibility of using ICRH as a fast ion source in W7-X relevant conditions. The SCENIC package is used to resolve the full wave propagation and absorption in a three-dimensional plasma equilibrium. The source of the Ion Cyclotron Range of Frequency (ICRF) wave is modelled in this work by an antenna formulation allowing its localisation in both the poloidal and toroidal directions. The actual antenna dimension and localization is therefore approximated with good agreement. The local wave deposition breaks the five-fold periodicity of W7-X. It appears that generation of fast ions is hindered by high collisionality and significant particle losses. The particle trapping mechanism induced by ICRH is found to enhance drift induced losses caused by the finite orbit width of trapped particles. The inclusion of a neoclassically resolved radial electric field is also investigated and shows a significant reduction of particle losses.

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Direct losses of fast particles in multiple-toroidicity stellarators

Cited by 3 publications

References 33 publications

Energetic particle physics in fusion research in preparation for burning plasma experiments

Energetic particle physics in fusion research in preparation for burning plasma experiments

The behaviour of magnetic ripple wells along field lines in current heliotrons and stellarators: comparison with a classical heliotron

ICRH induced particle losses in Wendelstein 7-X

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