Abstract Details
Abstracts
Author: Suying Jin
Requested Type: Poster
Submitted: 2026-04-13 20:55:07
Co-authors: A. K. Ram, S-G. Baek, P. T. Bonoli
Contact Info:
Massachusetts Institute of Technology
77 Massachusetts Ave
Cambridge, MA 02138
USA
Abstract Text:
Parametric decay instabilities (PDIs) are frequently observed during lower hybrid current drive (LHCD) in fusion plasmas. PDIs modify the launched spectrum in the edge region and are believed to be responsible for the anomalous degradation of core current drive at high densities, commonly referred to as the lower hybrid density limit. Reduced models based on three-wave coupling in homogeneous plasmas have provided a useful framework for interpreting these observations. However, the extent to which this framework can quantitatively predict the excited sideband spectra and saturated amplitudes remains unclear. We compare predictions from this standard modeling approach with PDI spectra observed in Alcator C-Mod experiments [1–2], highlighting where agreement is robust and where discrepancies persist. We also discuss ongoing efforts to extend these models to account for turbulent density fluctuations and background gradients, with the goal of improving their applicability to both current experiments and future reactor scenarios.
[1] Baek, S. G., et al. 2014. “Characterization of the Onset of Ion Cyclotron Parametric Decay Instability of Lower Hybrid Waves in a Diverted Tokamak.” Physics of Plasmas 21 (6): 061511.
[2] Baek, S.G., R.R. Parker, P.T. Bonoli, et al. 2015. “High Density LHRF Experiments in Alcator C-Mod and Implications for Reactor Scale Devices.” Nuclear Fusion 55 (4): 043009.
Characterization: 3.0
Comments: