ABSTRACT Meso-scale streamer has a radially elongated structure and is believed to enhance the ra... more ABSTRACT Meso-scale streamer has a radially elongated structure and is believed to enhance the radial transport. In order to study the control of the streamer, we demonstrated an end plate biasing to the streamer state in the PANTA linear plasma. During the end plate biasing, the electron density profile became more peaked, fluctuation was suppressed, the streamer structure was deconstructed, and the waveform became a periodic solitary state. The radial electric field only induced at around the end plate was found to play an important role for the streamer suppression.
Eigenmode analysis of geodesic acoustic modes (GAMs) driven by fast ions is performed, based on a... more Eigenmode analysis of geodesic acoustic modes (GAMs) driven by fast ions is performed, based on a set of gyrokinetic equations. Resonance to the magnetic drift of the fast ions can destabilize GAMs. A new branch is found in the family of GAMs, whose frequency is close to the magnetic drift frequency of the fast ions. The poloidal eigenfunction of this branch has bump structures in the poloidal direction where the resonance of the magnetic drift with the mode is strong. The ion heating rate by the GAMs is evaluated in the framework of quasi-linear theory. The heating is localized poloidally around the resonance locations. Owing to the bumps in the eigenfunction, the magnitude of the heating is much larger than that estimated without the magnetic drift resonance.
ABSTRACT Meso-scale streamer has a radially elongated structure and is believed to enhance the ra... more ABSTRACT Meso-scale streamer has a radially elongated structure and is believed to enhance the radial transport. In order to study the control of the streamer, we demonstrated an end plate biasing to the streamer state in the PANTA linear plasma. During the end plate biasing, the electron density profile became more peaked, fluctuation was suppressed, the streamer structure was deconstructed, and the waveform became a periodic solitary state. The radial electric field only induced at around the end plate was found to play an important role for the streamer suppression.
Eigenmode analysis of geodesic acoustic modes (GAMs) driven by fast ions is performed, based on a... more Eigenmode analysis of geodesic acoustic modes (GAMs) driven by fast ions is performed, based on a set of gyrokinetic equations. Resonance to the magnetic drift of the fast ions can destabilize GAMs. A new branch is found in the family of GAMs, whose frequency is close to the magnetic drift frequency of the fast ions. The poloidal eigenfunction of this branch has bump structures in the poloidal direction where the resonance of the magnetic drift with the mode is strong. The ion heating rate by the GAMs is evaluated in the framework of quasi-linear theory. The heating is localized poloidally around the resonance locations. Owing to the bumps in the eigenfunction, the magnitude of the heating is much larger than that estimated without the magnetic drift resonance.
Uploads
Papers by Maxime Lesur