Propagation of ion cyclotron emission in the DIII-D tokamak

• DOI: 10.1063/5.0250878
• Publication Date: 2025-03-18T14:52:52Z
• Authors: G. H. DeGrandchamp; W. W. Heidbrink; X. D. Du; J. B. Lestz; E.-H. Kim; S. Shiraiwa; M. A. Van Zeeland; J. A. Boedo; K. E. Thome; N. A. Crocker; R. I. Pinsker
• Keywords: DIII-D

Experiments in L- and H-mode plasmas performed on the DIII-D tokamak explored ion cyclotron emission (ICE) propagation via recently upgraded ICE diagnostic. The distance between plasma outer wall was scanned to alter evanescent region, which seen impact detection of runaway electron-driven whistler modes a comparable frequency range typical harmonics (f≳10fci) [Heidbrink et al., Plasma Phys. Controlled Fusion 61, 014007 (2018)]. In L-mode plasmas, core did not exhibit clear trends as plasma-wall altered. Instead, inadvertent changes fast density correlated with different fine structures; most spectral bands (spaced ∼150–200 kHz apart) were observed at highest density, just single band when nfast decreased by ∼ 40%. full-wave Petra-M code simulated through probes, agreeing experimental findings that these are likely compressional waves, propagate probe locations no dependence gap. Edge similarly unaffected distance. Unlike cases, there negligible edge distribution bulk profiles. However, ELM seemed closely tied behavior. Ultimately, dependencies distance, even largest gaps. This independence bodes well for similar diagnostics future tokamaks, might be placed further from high radiation areas without adversely impacting measurement capabilities.