The compact neutron spectrometer at ASDEX Upgrade

Giacomelli, L.; Zimbal, A.; Tittelmeier, K.; Schuhmacher, H.; Tardini, G.; Neu, R.

doi:10.1063/1.3660811

Cited by 33 publications

(27 citation statements)

References 14 publications

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“…Additionally there are some burn-up D-T reactions, but their rate is negligible compared to the amount of D-D reactions [16] [17]. Due to the high reactivity for deuterium energy above 50 keV, NBI injected deuterons can dominate the fusion reactions despite their lower density compared to the thermal D in the plasma.…”

Section: Modelling Assumptionsmentioning

confidence: 99%

“…In the ASDEX upgrade plasma discharges up to 2008 these three terms could not be detected separately, as no information on the neutron energy was recorded. The recently installed neutron spectrometry diagnostics [16][17] enables to deliver complementary experimental information, as soon as the characterization of the detector will enable to deconvolve the measured pulse height spectra. There can be, however, a signature of which component is dominant if one looks at how the neutron rate scales with a certain set of plasma parameters.…”

Section: Modelling Assumptionsmentioning

confidence: 99%

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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: Modelling Assumptionsmentioning

confidence: 99%

Section: Modelling Assumptionsmentioning

confidence: 99%

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

et al. 2013

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“…ASDEX Upgrade is also equipped with a suite of fast-ion diagnostics: fast-ion loss detectors (FILDs) [4][5][6], fast-ion D α (FIDA) [7], collective Thomson scattering (CTS) [8][9][10][11][12][13], neutron spectrometry [14,15], neutral particle analysers (NPA) [16,17] and γ -ray spectrometry [18]. These auxiliary heating systems and fast-ion diagnostics give unique opportunities to study fast ions in tokamak plasmas.…”

Section: Introductionmentioning

confidence: 99%

Combination of fast-ion diagnostics in velocity-space tomographies

et al. 2013

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Fast-ion D α (FIDA) and collective Thomson scattering (CTS) diagnostics provide indirect measurements of fastion velocity distribution functions in magnetically confined plasmas. Here we present the first prescription for velocity-space tomographic inversion of CTS and FIDA measurements that can use CTS and FIDA measurements together and that takes uncertainties in such measurements into account. Our prescription is general and could be applied to other diagnostics. We demonstrate tomographic reconstructions of an ASDEX Upgrade beam ion velocity distribution function. First, we compute synthetic measurements from two CTS views and two FIDA views using a TRANSP/NUBEAM simulation, and then we compute joint tomographic inversions in velocity-space from these. The overall shape of the 2D velocity distribution function and the location of the maxima at full and half beam injection energy are well reproduced in velocity-space tomographic inversions, if the noise level in the measurements is below 10%. Our results suggest that 2D fast-ion velocity distribution functions can be directly inferred from fast-ion measurements and their uncertainties, even if the measurements are taken with different diagnostic methods.

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“…So far three LOS's have been used and this may be increased to seven or eight LOS's in the future. In fusion plasma Doppler tomography at ASDEX Upgrade, we can combine the FIDA measurements with other measurements [22] such as collective Thomson scattering [20,[48][49][50][51], neutron emission spectroscopy or neutron yield measurements [52][53][54][55][56] or gamma-ray spectroscopy [57]. Similar combinations are possible at the tokamak DIII-D [27,45], the stellarator LHD [58][59][60] or the spherical tokamak MAST [61][62][63] as well as the next step fusion experiment ITER [64][65][66][67][68][69].…”

Section: Discussionmentioning

confidence: 99%

Doppler tomography in fusion plasmas and astrophysics

Salewski¹,

Geiger²,

Heidbrink³

et al. 2014

Plasma Phys. Control. Fusion

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Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D α (FIDA) spectroscopy measurements in magnetically confined plasma, the D α -photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright spots, spiral structures, and flow patterns. Fusion plasma Doppler tomography has lead to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography, and what can be learned by comparison of these applications.

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The compact neutron spectrometer at ASDEX Upgrade

Cited by 33 publications

References 14 publications

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

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

Combination of fast-ion diagnostics in velocity-space tomographies

Doppler tomography in fusion plasmas and astrophysics

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