Evidence for Fast-Ion Transport by Microturbulence

Heidbrink, W. W.; Park, J. M.; Murakami, M.; Petty, C. C.; Holcomb, C.T.; Zeeland, M. A. Van

doi:10.1103/physrevlett.103.175001

Cited by 74 publications

(101 citation statements)

References 19 publications

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“…This is implicitly included in the NUBEAM package, where single collision processes of suprathermal ions are computed. Furthermore, evidence for anomalous transport of fast ions has been found both on the experimental side, such as in D-alpha measurements [22] and NBI current drive studies [2] and in theory [23]. In some cases a finite diffusion coefficient of fast ions is invoked to ensure an accurate matching of the experimental neutron emission [7][24].…”

Section: Sensitivity To the Diffusion Coefficientmentioning

confidence: 99%

Simulation of the neutron rate in ASDEX Upgrade H-mode discharges

et al. 2013

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Abstract. The neutron rate is a direct indicator of the fusion performance in tokamaks. However, the accuracy of the measurement is limited by the wide range, covering several orders of magnitude, and by the delicate absolute calibration procedure.Moreover, a mere neutron counter does not distinguish between thermonuclear, beam-plasma and beam-beam fusion reactions. In this work we aim to use Monte Carlo simulations of the NBI deposition to improve our physics understanding of the correlation of the neutron yield with global plasma parameters.The modelling shows the beam-plasma reactions to be the main contribution to the neutron rate for P N BI > 5 MW. The comparison between experimental data and measurements allows to identify systematic calibration factors for different calibration phases over several years of acquisition. The quality of the kinetic profile measurements is shown to play an important role in reducing the scatter of the simulated neutron rate around the measured value. The sensitivity to Z ef f and to possible fast ion ‡ Corresponding author: git@ipp.mpg.deSimulation of the neutron rate in ASDEX Upgrade H-mode discharges 2 diffusion is investigated. Using an existing formula for the density dependence of Z ef f the agreement between theoretical prediction and experimental measurements is considerably improved. Finally we derive a scaling law for the measured neutron rate in ASDEX Upgrade H-mode discharges depending on global parameters, in excellent agreement with a simple physics derivation for beam-plasma neutrons.

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Section: Sensitivity To the Diffusion Coefficientmentioning

confidence: 99%

Simulation of the neutron rate in ASDEX Upgrade H-mode discharges

et al. 2013

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“…However, a series of experimental [5,6], theoretical [7] and numerical investigations [8][9][10] demonstrated that this conclusion might not hold for energetic ions created by neutral beam injection: in general, transport can be significant for particles characterized by 'intermediate' energies (E/T e 10) and small Larmor radii.…”

Section: Introductionmentioning

confidence: 99%

Assessment of turbulent beam ion redistribution in tokamaks through velocity space-dependent gyrokinetic analyses

Albergante¹,

Fasoli²,

Graves³

et al. 2012

Nucl. Fusion

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We present the interface between a gyrokinetic code and a guiding centre code dedicated to the study of fast ion turbulent transport. A set of velocity space-dependent (kinetic) transport quantities, representing the link between the two codes, is presented. The code suite is applied to DEMO and TCV plasmas. While negligible alpha particle transport is observed for both tokamaks, important beam ion redistribution is obtained for simulations of DEMO. Results for the TCV tokamak demonstrate that the influence of turbulent fields on fast ion transport strongly depends on the plasma scenario.

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“…Several types of modes selectively deplete or reorganize fast ions in particular velocity-space regions, for example sawteeth [1][2][3], Alfvén eigenmodes [4][5][6] and neoclassical tearing modes [7]. Turbulence also ejects ions selectively depending on their energy [8,9]. In particular, it is this selectivity of fast-ion depletion or reorganization in velocity space that can be quantified with velocity-space tomography.…”

Section: Introductionmentioning

confidence: 99%

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

Salewski¹,

Geiger²,

Nielsen³

et al. 2012

Nucl. Fusion

122

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We compute tomographies of 2D fast-ion velocity distribution functions from synthetic collective Thomson scattering (CTS) and fast-ion D α (FIDA) 1D measurements using a new reconstruction prescription. Contradicting conventional wisdom we demonstrate that one single 1D CTS or FIDA view suffices to compute accurate tomographies of arbitrary 2D functions under idealized conditions. Under simulated experimental conditions, single-view tomographies do not resemble the original fast-ion velocity distribution functions but nevertheless show their coarsest features. For CTS or FIDA systems with many simultaneous views on the same measurement volume, the resemblance improves with the number of available views, even if the resolution in each view is varied inversely proportional to the number of views, so that the total number of measurements in all views is the same. With a realistic four-view system, tomographies of a beam ion velocity distribution function at ASDEX Upgrade reproduce the general shape of the function and the location of the maxima at full and half injection energy of the beam ions. By applying our method to real many-view CTS or FIDA measurements, one could determine tomographies of 2D fast-ion velocity distribution functions experimentally.

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Evidence for Fast-Ion Transport by Microturbulence

Cited by 74 publications

References 19 publications

Simulation of the neutron rate in ASDEX Upgrade H-mode discharges

Simulation of the neutron rate in ASDEX Upgrade H-mode discharges

Assessment of turbulent beam ion redistribution in tokamaks through velocity space-dependent gyrokinetic analyses

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

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