Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X

Bannmann, Sebastian; Ford, O.; Hoefel, U.; Poloskei, Peter Zs; Pavone, Andrea; Kwak, Sehyun; Svensson, J.; Lazerson, Samuel; McNeely, P.; Rust, N.; Hartmann, Dirk; Pasch, E.; Fuchert, G.; Langenberg, Andreas; Pablant, N.; Brunner, Kai Jakob; Wolf, Robert C.

doi:10.1088/1361-6587/ad3c1d

Title: Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X

Journal Article · 18 April 2024 · Plasma Physics and Controlled Fusion

DOI: https://doi.org/10.1088/1361-6587/ad3c1d · OSTI ID:2352449

^[1]; Ford, O. ^[1]; Hoefel, U. ^[1];

^[1];

^[1]; Svensson, J. ^[1];

^[1]; McNeely, P. ^[1]; Rust, N. ^[1];

^[1]; Pasch, E. ^[1]; Fuchert, G. ^[1];

^[1];

^[2];

^[1];

^[1]

Max Planck Institute for Plasma Physics, Greifswald (Germany)
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

By employing Bayesian inference techniques, the full electron density profile from the plasma core to the edge of Wendelstein 7-X (W7-X) is inferred solely from neutral hydrogen beam and halo Balmer-α (Hα) emission data. The halo is a cloud of neutrals forming in the vicinity of the injected neutral beam due to multiple charge exchange reactions. W7-X is equipped with several neutral hydrogen beam heating sources and an Hα spectroscopy system that views these sources from different angles and penetration depths in the plasma. As the beam and halo emission form complex spectra for each spatial point that are non-linearly dependent on the plasma density profile and other parameters, a complete model from the neutral beam injection and halo formation through to the spectroscopic measurements is required. The model is used here to infer electron density profiles for a range of common W7-X plasma scenarios. The inferred profiles show good agreement with profiles determined by the Thomson scattering and interferometry diagnostics across a broad range of absolute densities without any changes to the input or fitting parameters. The time evolution of the density profile in a discharge with continuous core density peaking is successfully reconstructed, demonstrating sufficient spatial resolution to infer strongly shaped profiles. Furthermore, it is shown as a proof of concept that the model is also able to infer the main ion temperature profile using the same data set.

View Accepted Manuscript (DOE)

Cite

Export

Save

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 2352449

Journal Information:: Plasma Physics and Controlled Fusion, Journal Name: Plasma Physics and Controlled Fusion Journal Issue: 6 Vol. 66; ISSN 0741-3335

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

References (23)

Current status of the neutral beam heating system of W7-X McNeely, Paul; Barlak, Marek; Baldzuhn, Jürgen Fusion Engineering and Design, Vol. 88, Issue 6-8 https://doi.org/10.1016/j.fusengdes.2013.03.006	journal	October 2013
Bayesian modeling of collisional-radiative models applicable to thermal helium beam plasma diagnostics Flom, E.; Krychowiak, M.; Schmitz, O. Nuclear Materials and Energy, Vol. 33 https://doi.org/10.1016/j.nme.2022.101269	journal	October 2022
Demonstration of reduced neoclassical energy transport in Wendelstein 7-X Beidler, C. D.; Smith, H. M.; Alonso, A. Nature, Vol. 596, Issue 7871 https://doi.org/10.1038/s41586-021-03687-w 2021	journal	August 2021
The motional Stark effect: Overview and future development (invited) Levinton, F. M. Review of Scientific Instruments, Vol. 70, Issue 1 https://doi.org/10.1063/1.1149316	journal	January 1999
The Thomson scattering system at Wendelstein 7-X Pasch, E.; Beurskens, M. N. A.; Bozhenkov, S. A. Review of Scientific Instruments, Vol. 87, Issue 11 https://doi.org/10.1063/1.4962248	journal	September 2016
Active spectroscopy measurements of the deuterium temperature, rotation, and density from the core to scrape off layer on the DIII-D tokamak (invited) Haskey, S. R.; Grierson, B. A.; Stagner, L. Review of Scientific Instruments, Vol. 89, Issue 10 https://doi.org/10.1063/1.5038349	journal	October 2018
In situ wavelength calibration system for the X-ray Imaging Crystal Spectrometer (XICS) on W7-X Kring, J.; Pablant, N.; Langenberg, A. Review of Scientific Instruments, Vol. 89, Issue 10 https://doi.org/10.1063/1.5038809	journal	October 2018
Inference of temperature and density profiles via forward modeling of an x-ray imaging crystal spectrometer within the Minerva Bayesian analysis framework Langenberg, A.; Svensson, J.; Marchuk, O. Review of Scientific Instruments, Vol. 90, Issue 6 https://doi.org/10.1063/1.5086283	journal	June 2019
Charge exchange recombination spectroscopy at Wendelstein 7-X Ford, O. P.; Vanó, L.; Alonso, J. A. Review of Scientific Instruments, Vol. 91, Issue 2 https://doi.org/10.1063/1.5132936	journal	February 2020
Beam emission spectroscopy as a comprehensive plasma diagnostic tool Mandl, W.; Wolf, R. C.; Hellermann, M. G. von Plasma Physics and Controlled Fusion, Vol. 35, Issue 10 https://doi.org/10.1088/0741-3335/35/10/003	journal	October 1993
Direct measurement of JET local deuteron densities by neural network modelling of Balmer alpha beam emission spectra Svensson, J.; Hellermann, M. von; König, R. W. T. Plasma Physics and Controlled Fusion, Vol. 43, Issue 4 https://doi.org/10.1088/0741-3335/43/4/302	journal	March 2001
Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR Schmitz, O.; Beigman, I. L.; Vainshtein, L. A. Plasma Physics and Controlled Fusion, Vol. 50, Issue 11 https://doi.org/10.1088/0741-3335/50/11/115004	journal	September 2008
Bayesian electron density inference from JET lithium beam emission spectra using Gaussian processes Kwak, Sehyun; Svensson, J.; Brix, M. Nuclear Fusion, Vol. 57, Issue 3 https://doi.org/10.1088/1741-4326/aa5072	journal	January 2017
Major results from the first plasma campaign of the Wendelstein 7-X stellarator Wolf, R. C.; Ali, A.; Alonso, A. Nuclear Fusion, Vol. 57, Issue 10 https://doi.org/10.1088/1741-4326/aa770d	journal	July 2017
Deuterium temperature, drift velocity, and density measurements in non-Maxwellian plasmas at ASDEX Upgrade Salewski, M.; Geiger, B.; Jacobsen, A. S. Nuclear Fusion, Vol. 58, Issue 3 https://doi.org/10.1088/1741-4326/aaa6e1	journal	February 2018
Measurements of plasma parameters in the divertor island of Wendelstein 7-X through line-ratio spectroscopy on helium Barbui, T.; Krychowiak, M.; Schmitz, O. Nuclear Fusion, Vol. 60, Issue 10 https://doi.org/10.1088/1741-4326/aba9eb 2020	journal	September 2020
First neutral beam experiments on Wendelstein 7-X Lazerson, Samuel A.; Ford, Oliver; Äkaslompolö, Simppa Nuclear Fusion, Vol. 61, Issue 9 https://doi.org/10.1088/1741-4326/ac121c 2021	journal	July 2021
Experimental characterization of the active and passive fast-ion H-alpha emission in W7-X using FIDASIM Poloskei, Peter Zs.; Geiger, B.; Jansen van Vuuren, A. Nuclear Fusion, Vol. 64, Issue 2 https://doi.org/10.1088/1741-4326/ad0dd4	journal	December 2023
The Thomson scattering diagnostic at Wendelstein 7-X and its performance in the first operation phase Bozhenkov, S. A.; Beurskens, M.; Molin, A. Dal Journal of Instrumentation, Vol. 12, Issue 10 https://doi.org/10.1088/1748-0221/12/10/P10004	journal	October 2017
Real-time dispersion interferometry for density feedback in fusion devices Brunner, K. J.; Akiyama, T.; Hirsch, M. Journal of Instrumentation, Vol. 13, Issue 09 https://doi.org/10.1088/1748-0221/13/09/P09002	journal	September 2018
Measurements of visible bremsstrahlung and automatic Bayesian inference of the effective plasma charge Z _eff at W7-X Pavone, A.; Hergenhahn, U.; Krychowiak, M. Journal of Instrumentation, Vol. 14, Issue 10 https://doi.org/10.1088/1748-0221/14/10/C10003	journal	October 2019
Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X Bannmann, S.; Ford, O.; Hoefel, U. Journal of Instrumentation, Vol. 18, Issue 10 https://doi.org/10.1088/1748-0221/18/10/P10029	journal	October 2023
Wendelstein 7-X Program—Demonstration of a Stellarator Option for Fusion Energy Wolf, R. C.; Beidler, C. D.; Dinklage, A. IEEE Transactions on Plasma Science, Vol. 44, Issue 9 https://doi.org/10.1109/TPS.2016.2564919	journal	September 2016

Similar Records

Measurements of radial neutral density profiles from Balmer-α emission in Wendelstein 7-X

Journal Article · 2025 · Plasma Physics and Controlled Fusion · OSTI ID:2586624

Romba, T.; Reimold, F.; Ford, O. P.; +2 more

Visible core spectroscopy at Wendelstein 7-X

Journal Article · 2024 · Review of Scientific Instruments · OSTI ID:2437698

Ford, O. P.; Langenberg, A.; Romba, T.; +14 more

Charge exchange recombination spectroscopy at Wendelstein 7-X

Journal Article · 2020 · Review of Scientific Instruments · OSTI ID:1616951

Ford, O. P.; Vanó, L.; Alonso, J. A.; +23 more

Related Subjects

forward modeling
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Bayesian inference
Minerva
W7X
beam emission spectroscopy
electron density profile
halo emission
neutral beam injection

Title: Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X

Citation Formats

References (23)

Similar Records

Related Subjects