Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection
© 2020 IAEA, Vienna We present a fully Bayesian approach for the inference of radial profiles of impurity transport coefficients and compare its results to neoclassical, gyrofluid and gyrokinetic modeling. Using nested sampling, the Bayesian impurity transport inference (BITE) framework can handle c...
| Main Authors: | , , , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2021
|
| Online Access: | https://hdl.handle.net/1721.1/133298 |
| _version_ | 1826214207190728704 |
|---|---|
| author | Sciortino, F Howard, NT Marmar, ES Odstrcil, T Cao, NM Dux, R Hubbard, AE Hughes, JW Irby, JH Marzouk, YM Milanese, LM Reinke, ML Rice, JE Rodriguez-Fernandez, P |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center Sciortino, F Howard, NT Marmar, ES Odstrcil, T Cao, NM Dux, R Hubbard, AE Hughes, JW Irby, JH Marzouk, YM Milanese, LM Reinke, ML Rice, JE Rodriguez-Fernandez, P |
| author_sort | Sciortino, F |
| collection | MIT |
| description | © 2020 IAEA, Vienna We present a fully Bayesian approach for the inference of radial profiles of impurity transport coefficients and compare its results to neoclassical, gyrofluid and gyrokinetic modeling. Using nested sampling, the Bayesian impurity transport inference (BITE) framework can handle complex parameter spaces with multiple possible solutions, offering great advantages in interpretative power and reliability with respect to previously demonstrated methods. BITE employs a forward model based on the pySTRAHL package, built on the success of the well-known STRAHL code (Dux 2003 Fusion Sci Technol. 44 708-15), to simulate impurity transport in magnetically-confined plasmas. In this paper, we focus on calcium (Ca, Z = 20) laser blow-off injections into Alcator C-Mod plasmas. Multiple Ca atomic lines are diagnosed via high-resolution x-ray imaging crystal spectroscopy and vacuum ultra-violet measurements. We analyze a sawtoothing I-mode discharge for which neoclassical and turbulent (quasilinear and non-linear) predictions are also obtained. We find good agreement in diffusion across the entire radial extent, while turbulent convection and density profile peaking are estimated to be larger in experiment than suggested by theory. Efforts and challenges associated with the inference of experimental pedestal impurity transport are discussed. |
| first_indexed | 2024-09-23T16:01:47Z |
| format | Article |
| id | mit-1721.1/133298 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T16:01:47Z |
| publishDate | 2021 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1332982023-12-19T21:24:18Z Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection Sciortino, F Howard, NT Marmar, ES Odstrcil, T Cao, NM Dux, R Hubbard, AE Hughes, JW Irby, JH Marzouk, YM Milanese, LM Reinke, ML Rice, JE Rodriguez-Fernandez, P Massachusetts Institute of Technology. Plasma Science and Fusion Center Massachusetts Institute of Technology. Department of Physics Massachusetts Institute of Technology. Department of Aeronautics and Astronautics © 2020 IAEA, Vienna We present a fully Bayesian approach for the inference of radial profiles of impurity transport coefficients and compare its results to neoclassical, gyrofluid and gyrokinetic modeling. Using nested sampling, the Bayesian impurity transport inference (BITE) framework can handle complex parameter spaces with multiple possible solutions, offering great advantages in interpretative power and reliability with respect to previously demonstrated methods. BITE employs a forward model based on the pySTRAHL package, built on the success of the well-known STRAHL code (Dux 2003 Fusion Sci Technol. 44 708-15), to simulate impurity transport in magnetically-confined plasmas. In this paper, we focus on calcium (Ca, Z = 20) laser blow-off injections into Alcator C-Mod plasmas. Multiple Ca atomic lines are diagnosed via high-resolution x-ray imaging crystal spectroscopy and vacuum ultra-violet measurements. We analyze a sawtoothing I-mode discharge for which neoclassical and turbulent (quasilinear and non-linear) predictions are also obtained. We find good agreement in diffusion across the entire radial extent, while turbulent convection and density profile peaking are estimated to be larger in experiment than suggested by theory. Efforts and challenges associated with the inference of experimental pedestal impurity transport are discussed. 2021-10-27T19:52:00Z 2021-10-27T19:52:00Z 2020 2021-05-03T15:47:53Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/133298 en 10.1088/1741-4326/ABAE85 Nuclear Fusion Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf IOP Publishing arXiv |
| spellingShingle | Sciortino, F Howard, NT Marmar, ES Odstrcil, T Cao, NM Dux, R Hubbard, AE Hughes, JW Irby, JH Marzouk, YM Milanese, LM Reinke, ML Rice, JE Rodriguez-Fernandez, P Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title | Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title_full | Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title_fullStr | Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title_full_unstemmed | Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title_short | Inference of experimental radial impurity transport on Alcator C-Mod: Bayesian parameter estimation and model selection |
| title_sort | inference of experimental radial impurity transport on alcator c mod bayesian parameter estimation and model selection |
| url | https://hdl.handle.net/1721.1/133298 |
| work_keys_str_mv | AT sciortinof inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT howardnt inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT marmares inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT odstrcilt inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT caonm inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT duxr inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT hubbardae inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT hughesjw inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT irbyjh inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT marzoukym inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT milaneselm inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT reinkeml inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT riceje inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection AT rodriguezfernandezp inferenceofexperimentalradialimpuritytransportonalcatorcmodbayesianparameterestimationandmodelselection |