Integrated data analysis of fast-ion measurements by velocity-space tomography

Transcription

1 Integrated data analysis of fast-ion measurements by velocity-space tomography Technical University of Denmark Department of Physics M.Nocente, B.Geiger, A.S.Jacobsen, F.Binda, C.Cazzaniga, G. Gorini, G.Ericsson, J.Eriksson, W.W. Heidbrink, C.Hellesen, A.Hjalmarsson, V.G.Kiptily, S.B.Korsholm, T.Koskela, T.Kurki-Suonio, F.Leipold, J.Madsen, D.Moseev, S.K.Nielsen, J.Rasmussen, L.Stagner, M.Schneider, S.E.Sharapov, M.Stejner, M.Tardocchi, M.Weiland 2 nd IAEA TM on Fusion Data Processing, Validation and Analysis 30 May - 2 June 2017, Cambridge, MA, USA

2 Outline Introduction to velocity-space tomography GRS/NES-based velocity-space tomography at JET FIDA-based velocity-space tomography at ASDEX Upgrade Summary and outlook 2

3 Introduction to velocity-space tomography Forward problem WF = S Distribution function F Matrix W Measurements S Inverse problem Salewski et al (2011,12,13,14,15,16,17) NF 3

4 Outline Introduction to velocity-space tomography GRS/NES-based velocity-space tomography at JET FIDA-based velocity-space tomography at ASDEX Upgrade Summary and outlook 4

5 Neutron emission and gamma-ray spectrometry at JET Perpendicular view Φ=90 (LOS, B) Oblique view Φ=47 (LOS, B) Eriksson et al (2015) NF 5

6 NES measurements 3 simultaneously measured spectra in JET # MW NBI + 3 MW 3rd harmonic ICRF-heating Yellow: Used for inversion 6 Salewski et al (2017) NF

7 GRS measurements 2 GRS spectra in JET #86459 High-resolution High-purity Germanium detector (1keV over 10 MeV) Two competing reactions 7 Salewski et al (2017) NF

8 Velocity-space observation regions Weight functions w: Heidbrink et al (2007) PPCF Signal/ion Discretize: Reject data if w is 1) is outside the target velocity space. 2) covers the velocity space below 120 kev. 8 Jacobsen et al (2014) RSI, Jacobsen et al (2015) NF

9 Velocity-space observation regions TOFOR Diamond 5 detectors 3 typical Doppler shifts NE213 GRS 2868 kev NES: Jacobsen et al (2014) RSI, Jacobsen et al (2015) NF GRS: Salewski et al (2015) NF, Salewski et al (2016a) NF GRS 3367 kev 9 Low Medium High

10 Inversion by 1 st -order Tikhonov regularization Forward problem: Inverse problem: 10

11 Velocity-space tomography vs. simulation Basic features agree: Tail length, tail width. Barrier region suggests low densities above 2 MeV. Velocity-space tomography confirms the barrier experimentally. [a.u.] [a.u.] [a.u.] Salewski et al (2017) NF 11

12 What if we only use NES or GRS? Inversions rely on integrated data analysis NES only or GRS only do not work well 12

13 Outline Introduction to velocity-space tomography GRS/NES-based velocity-space tomography at JET FIDA-based velocity-space tomography at ASDEX Upgrade Summary and outlook 13

14 FIDA spectroscopy at ASDEX Upgrade Weiland et al (2016) PPCF 14

15 Prior information: What do we know? F is non-negative. Null-measurements of FIDA light (E,p) position of NBI peaks at E, E/2, E/3 15 Salewski et al (2016b) NF

16 High-definition tomography: Inversion using prior information Simulation Without prior information Artifacts With prior information No visible artifacts Salewski et al (2016b) NF 16

17 Tomography movie of a sawtooth crash Upper panel: Measurement of fast ion density n f = fdedp Lower panel: tomographic inversion movie fit to data points 100 frames 5 spectra per frame 100 data points per spectrum Salewski et al (2016b) NF 17

18 Sawteeth: FIDA tomography vs. TRANSP AUG #32323 TRANSP FIDA Fairly good agreement Measured crashes smaller than simulated crashes. No measured crashes for p <0.25 in agreement with Kolesnichenko (1996) NF and disagreement with TRANSP. Salewski et al (2016b) NF 18

19 For two-view FIDA systems: Numeric simulation as prior information Not using TRANSP as prior information Using TRANSP as prior information 19 MUCH easier! Salewski et al (2016b) NF

20 Reconstruction of differences from TRANSP Cases with and without TRANSP as prior information give consistent results for the 5-view case. Works for 2 FIDA views. 20 Salewski et al (2016b) NF

21 Optimal experimental design for fast-ion diagnostic sets ASDEX Upgrade went from 3 to 5 FIDA views. Chose 2 viewing angles to best complement the other 3. Minimize quality parameter 85 and 50 are best. 3 existing viewing angles Weiland et al (2016) PPCF 21

22 Velocity-space observation regions NES FIDA CTS 1-step GRS W has vastly different forms for the different diagnostics. Known already. NPA: Heidbrink et al (2007) PPCF CTS: Salewski et al (2011) NF 2-step GRS FIDA: Salewski et al (2014) PPCF NES: Jacobsen et al (2015) NF GRS-2: Salewski et al (2015) NF GRS-1: Salewski et al (2016) NF 22

23 Summary Velocity-space tomography reveals new physics. Converts complex data to straightforward 2D images Combines diagnostics Accounts for nuisance parameters MeV range ion velocity-space tomography based on 5 NES/GRS spectra agrees well with simulations FIDA-based velocity-space movies at ASDEX Upgrade Velocity-space studies of sawtooth crashes confirm pitch selectivity Outlook Increase fast-ion measurement data at AUG and JET Use thermal ion signals Demonstrate approach on other machines Apply: Alfven modes, NTM, sawteeth, burning plasma Improve inversion methods Go 3D (spatial coordinate, constants-of-motion or EPmRm) Stagner (this conference) Thank you for your attention! 23