Investigation of High-Te Discrepancies Between ECE and TS Using Super-Resolved Thomson Scattering at DIII-D

POSTER

Abstract

Significant discrepancies have been observed in the JET tokamak [1] between electron temperature (Te) profiles measured by Electron Cyclotron Emission (ECE) and Thomson Scattering (TS). These discrepancies have also been observed in high Te DIII-D plasmas. At DIII-D, ECE provides high temporal resolution (~500 kHz), while TS is limited to ≤200 Hz, complicating time-resolved comparisons and analysis of fast events. A statistical survey of high-performance DIII-D discharges is conducted to investigate the occurrence and magnitude of discrepancies depending on plasma conditions and identify correlations with ohmic versus auxiliary heating methods like ECH and NBI. Observed patterns are evaluated against proposed explanations including optical depth effects, equilibrium mapping inaccuracies, and non-Maxwellian energy distributions. This project uses the Diag2Diag machine learning framework to generate super-resolved TS (SRTS) profiles at high time resolutions [2], enabling synchronized comparisons between the two Te diagnostics. Based on these statistical observations, preliminary models are proposed to characterize and predict when ECE-TS discrepancies emerge. Insights from this project serve to improve the accuracy of Te profiling in diverse plasma scenarios at DIII-D and future fusion devices.

[1] Fontana M. et al, Phys. Plasmas 30, 122503 (2023)

[2] Jalalvand A. et. al https://arxiv.org/abs/2405.05908, accepted to be published in Nat.Comm, (2025)

*Work supported by the U.S. DOE, Office of Science, WDTS under the SULI program. This work was performed under the auspices of the U.S. DOE by General Atomics under Contract DE-NA0001808. In addition, this research was supported by the U.S. DOE, under Awards DE-SC0024527, DE-SC0015480, DE-SC0022270, DE- SC0022272, DE-SC0023061, and DE-FG02-05ER54809.

Presenters

  • Gabrielle Elise Bladon

    • Auburn University

Authors

  • Gabrielle Elise Bladon

    • Auburn University

  • Azarakhsh Jalalvand

    • Princeton University

  • SangKyeun Kim

    • Princeton Plasma Physics Laboratory (PPPL)

  • A Stephane BIWOLE

    • Massachusetts Institute of Technology
    • Massachusetts Institute of Technology, Boston, MA, United States of America

  • Dmitriy M Orlov

    • University of California, San Diego

  • Bradley Andrew

    • Auburn University

  • Suk-Ho Hong

    • General Atomics

  • Egemen Kolemen

    • Princeton University

  • Evdokiya G Kostadinova

    • Auburn University