@article{oai:nifs-repository.repo.nii.ac.jp:00010909,
 author = {IDO,  Takeshi and OSAKABE,  Masaki and LESUR, M. and SHIMIZU,  Akihiro and OGAWA,  Kunihoro and TOI,  Kazuo and NISHIURA,  Masaki and Kato,  S. and Sasaki, Makoto and IDA,  Katsumi and INAGAKI,  Shigeru and ITOH,  Sanae -I. and the, LHD Experiment Group},
 journal = {Physical Review Letters},
 month = {Jan},
 note = {Abrupt and strong excitation of a mode has been observed when the frequency of a chirping energetic-particle driven geodesic acoustic mode (EGAM) reaches twice the geodesic acoustic mode (GAM) frequency. The frequency of the secondary mode is the GAM frequency, which is a half-frequency of the primary EGAM. Based on the analysis of spatial structures, the secondary mode is identified as a GAM. The phase relation between the secondary mode and the primary EGAM is locked, and the evolution of the growth rate of the secondary mode indicates nonlinear excitation. The results suggest that the primary mode (EGAM) contributes to nonlinear destabilization of a subcritical mode.},
 title = {Strong Destabilization of Stable Modes with a Half-Frequency Associated with Chirping Geodesic Acoustic Modes in the Large Helical Device},
 volume = {116},
 year = {2016}
}