Physics Design for ARIES-CS

Ku, L. P.; Garabedian, P. R.; Lyon, J. F.; Turnbull, A. D.; Grossman, A.; Mau, T. K.; Zarnstorff, M. C.; Team, Aries

doi:10.13182/fst08-a1899

Cited by 40 publications

(55 citation statements)

References 35 publications

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“…A small effective helical ripple ef f does not guarantee an acceptable loss of energetic particles. Following collisonless particle orbits to derive a loss metric is an effective way to improve stellarator configurations [15] and should be included in a more complete study of QA configurations .…”

Section: Discussionmentioning

confidence: 99%

“…Theoretical and numerical investigations of QA stellarators were pioneered by Nührenberg and Garabedian [12], [13], [14], and the potential of a quasi-axisymmetric stellarator as a fusion power reactor has been studied [15]. An experimental device [16], the National Compact Stellarator Experiment (NCSX), was proposed in the late 1990's, but the construction was terminated in 2008 during the final stages of manufacture and assembly.…”

Section: Introductionmentioning

confidence: 99%

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Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry

Boozer¹

2009

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If quasi-axisymmetry is preserved, non-axisymmetric shaping can be used to design tokamaks that do not require current drive, are resilient to disruptions, and have robust plasma stability without feedback. Suggestions for addressing the critical issues of tokamaks can only be validated when presented with sufficient specificity that validating experiments can be designed. The purpose of this paper is provide that specificity for non-axisymmetric shaping. To our knowledge, no other suggestions for the solution of a number of tokamak issues, such as disruptions, have reached this level of specificity. Sequences of three-field-period quasi-axisymmetric plasmas are studied. These sequences address the questions: (1) What can be achieved at various levels of non-axisymmetric shaping? (2) What simplifications to the coils can be achieved by going to a larger aspect ratio? (3) What range of shaping can be achieved in a single experimental facility? The sequences of plasmas found in this study provide a set of interesting and potentially important configurations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry

Boozer¹

2009

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“…Plasma beta is set to be 4.0%. Fourier coefficients describing the target plasma boundary of the A=6.0 configuration are taken from Table 1 of reference [11], and scaled appropriately.…”

Section: Improved Coil Designmentioning

confidence: 99%

Recent advances in stellarator optimization

et al. 2017

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Computational optimization has revolutionized the field of stellarator design. To date, optimizations have focused primarily on optimization of neoclassical confinement and ideal MHD stability, although limited optimization of other parameters has also been performed.The purpose of this paper is to outline a select set of new concepts for stellarator optimization that, when taken as a group, present a significant step forward in the stellarator concept.One of the criticisms that has been leveled at existing methods of design is the complexity of the resultant field coils. Recently, a new coil optimization code -COILOPT++, which uses a spline instead of a Fourier representation of the coils, -was written and included in the STELLOPT suite of codes. The advantage of this method is that it allows the addition of real space constraints on the locations of the coils. The code has been tested by generating coil designs for optimized quasi-axisymmetric stellarator plasma configurations of different aspect ratios. As an initial exercise, a constraint that the windings be vertical 1 was placed on large major radius half of the non-planar coils. Further constraints were also imposed that guaranteed that sector blanket modules could be removed from between the coils, enabling a sector maintenance scheme. Results of this exercise will be presented.New ideas on methods for the optimization of turbulent transport have garnered much attention since these methods have led to design concepts that are calculated to have reduced turbulent heat loss. We have explored possibilities for generating an experimental database to test whether the reduction in transport that is predicted is consistent with experimental observations. To this end, a series of equilibria that can be made in the now latent QUASAR experiment have been identified that will test the predicted transport scalings. Fast particle confinement studies aimed at developing a generalized optimization algorithm are also discussed. A new algorithm developed for the design of the scraper element on W7-X is presented along with ideas for automating the optimization approach.

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“…The characteristics of energetic-ion-driven AEs and their impacts on energetic-ion confinement have been intensively investigated in major tokamaks [1]. On author's e-mail: toi@lhd.nifs.ac.jp the other hand, a helical/stellarator-type reactor, for instance, ARIES CS [2], is being designed on the basis of an operation scenario with high-density (∼5 × 10 20 m −3 )…”

Section: Introductionmentioning

confidence: 99%

Energetic-Ion-Driven Global Instabilities Observed in the Large Helical Device and Their Effects on Energetic Ion Confinement

Toi

2013

Plasma and Fusion Research

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This paper reviews various global instabilities destabilized by tangential neutral beam injection (NBI) in the Large Helical Device (LHD) plasmas. These global modes are toroidal Alfvén eigenmodes (TAEs), which are also observed in tokamak plasmas, and helicity-induced Alfvén eigenmodes (HAEs) which are observed only in three-dimensional plasmas such as LHD plasmas. Moreover, reversed magnetic shear Alfvén eigenmodes (RSAEs) are observed in a reversed magnetic shear (RS) plasma in the LHD, where the sign of the magnetic shear changes from positive in the plasma central region to negative in the plasma peripheral region. The RSAEs exhibit a characteristic frequency sweeping due to temporal evolution of the rotational transform profile. In the RS plasma, the energetic-ion-driven geodesic acoustic mode (GAM) is also excited. The GAM interacts nonlinearly with the RSAEs and generates a multitude of frequency sweeping modes through a three-wavecoupling process. The TAEs and GAM exhibit various types of nonlinear evolution, that is, pitchfork splitting and rapid frequency chirp-up and/or chirp-down. The linear and nonlinear characteristics of these energetic-iondriven global instabilities in the LHD are compared with those observed in tokamak plasmas. TAE bursts having rapid frequency chirp-down induce redistribution and/or loss of energetic ions. Future important issues are briefly described.

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Physics Design for ARIES-CS

Cited by 40 publications

References 35 publications

Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry

Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry

Recent advances in stellarator optimization

Energetic-Ion-Driven Global Instabilities Observed in the Large Helical Device and Their Effects on Energetic Ion Confinement

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