Evidence of 'two plasmon' decay of energetic particle induced geodesic acoustic mode. (17th June 2021)

• Record Type: Journal Article
• Authors: Qiu, Zhiyong; Chen, Liu; Zonca, Fulvio; Falessi, Matteo Valerio
• Is Part Of: New journal of physics. Volume 23:Number 6(2021)
• Publication Date: 2021-06-17
• Subjects: energetic particle -- magnetically confined fusion -- nonlinear mode coupling -- two plasmon decay -- geodesic acoustic mode -- Gyrokinetic theory; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/ac047a
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: Secondary low frequency mode generation by energetic particle induced geodesic acoustic mode (EGAM) observed in LHD experiment is studied using nonlinear gyrokinetic theory. It is found that the EGAM frequency can be significantly higher than local geodesic acoustic mode (GAM) frequency in low collisionality plasmas, and it can decay into two GAMs as its frequency approaches twice GAM frequency, in a process analogous to the well-known two plasmon decay instability. The condition for this process to occur is also discussed.