Study of GAMs on Tore Supra using Doppler backscattering
Event details
| Date | 10.12.2012 |
| Hour | 10:30 › 11:30 |
| Speaker | Dr. Laure Vermare |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
Geodesic Acoustic Modes (GAMs) have only recently been detected on Tore Supra by using the MUltiple SIgnal Classification (MUSIC) algorithm to access the temporal evolution of the perpendicular velocity of density fluctuations. The high resolution obtained by this method allows us to follow the temporal evolution of the characteristics of the GAMs such as the amplitude and the frequency.
The tokamak Tore Supra has three channels of Doppler backscattering. Two channels covering typically the plasma edge from r/a=1.2 to r/a=0.8 and the gradient region r/a=0.9 to r/a=0.6 using respectively X‑mode and O-mode polarisation are installed in the equatorial plane while the third channel is installed in vertical view with a location at a toroidal angle of 120° from the equatorial system.
Oscillations of the perpendicular velocity have been observed near the edge in numerous discharges using the different channels. Oscillations related to GAMs are generally observed with a typical frequency of about 10kHz, which is found to scale with Cs/R, when the additional heating power (ICRH) is varied.
This paper presents investigations of GAMs on Tore Supra plasmas taking advantage of the High temporal resolution given by the MUSIC algorithm and using both equatorial and vertical Doppler systems.
The work in progress on the evolution of the GAM level with plasma parameters such as safety factor and collisionality will be discussed.
First measurements performed on TCV will be also presented.
The tokamak Tore Supra has three channels of Doppler backscattering. Two channels covering typically the plasma edge from r/a=1.2 to r/a=0.8 and the gradient region r/a=0.9 to r/a=0.6 using respectively X‑mode and O-mode polarisation are installed in the equatorial plane while the third channel is installed in vertical view with a location at a toroidal angle of 120° from the equatorial system.
Oscillations of the perpendicular velocity have been observed near the edge in numerous discharges using the different channels. Oscillations related to GAMs are generally observed with a typical frequency of about 10kHz, which is found to scale with Cs/R, when the additional heating power (ICRH) is varied.
This paper presents investigations of GAMs on Tore Supra plasmas taking advantage of the High temporal resolution given by the MUSIC algorithm and using both equatorial and vertical Doppler systems.
The work in progress on the evolution of the GAM level with plasma parameters such as safety factor and collisionality will be discussed.
First measurements performed on TCV will be also presented.
Practical information
- Expert
- Free
- This event is internal
Organizer
- Prof. P. Ricci
Contact
- Prof. P. Ricci