First High-Power Helicon Results From DIII-D

• Published in: Nuclear fusion
• Main Authors: Pinsker, Robert I., Van Compernolle, Bart, Tang, Shawn X., Lestz, Jeff, Moeller, Charles P., Petty, Craig, Dupuy, Alexandre, Squire, Jared P., Garofalo, Andrea M., Porkolab, Miklos, Rost, J. C., Baek, Seung-Gyou, Nagy, Alexander, Chowdhury, Satyajit, Crocker, Neal A., DeGrandchamp, Genevieve, McLean, Adam G., Gage, Kenneth Ryan, Marinoni, Alessandro, Martin, Elijah Henry, Ronchi, Gilson
• Format: Journal Article
• Language: English
• Published: United States IOP Science 10.09.2024
• ISSN: 0029-5515

Abstract More than 0.6 MW of rf power at 476 MHz has been coupled to DIII-D plasmas by launching helicon (whistler) waves with a traveling-wave antenna (comb-line) in the fast-wave polarization which resulted in the observation of electron heating of the core plasma with single-pass absorption based on ray-tracing in L-mode discharges. The coupling performance of the wide 30-element comb-line traveling-wave antenna has been consistent with expectations based on the 2015-2016 experiments on DIII-D with a low-power 12-element prototype. The conditioning process that was necessary to carry out high-power experiments is discussed; rf-specific impurities have not been observed. Parametric decay instabilities (PDI) have been observed and are being investigated as a potential edge absorption mechanism.