"Turbulence and its interaction with magnetic topology"
Event details
| Date | 07.11.2014 |
| Hour | 09:30 › 10:30 |
| Speaker | Dr. N. Vianello, Consorzio RFX, C.so Stati Uniti 4, Padova, Italy |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
The paradigm of 2D axisymmetry in magnetically fusion devices is being progressively abandoned in favor of a more realistic description of the 3D geometry of the magnetic field. Indeed, apart from intrinsic 3D configurations such as stellarators, the effects of non-axisymmetric magnetic field are becoming a fundamental issue also for tokamaks, where magnetic perturbations are used for ELMs control, and Reversed Field Pinches (RFPs), with the observation of a spontaneous self organized helical state in high current regimes in. Experimental observations in the RFPs have revealed that a magnetic island or an edge helical ripple, generates a three dimensional flow pattern as the result of ambipolar constraints and this mechanism is likely to act independently of the configuration.
The way a 3D field interacts with plasma turbulence is presently a matter of active research. Indeed it is well known that fluctuations carry a substantial fraction of particle and energy transport, in particular in the periphery of confined plasma. In this region transport is dominated by the presence of coherent structure/blobs, i.e. fluctuations localized in space and time which carry energy and particles through their convective motion and/or their mutual interaction. These structures exhibit the feature of filaments elongated in the direction of the magnetic field: the presence of a non axisymmetric magnetic field is believed to modify their properties acting on their source of free energy through the modulation of typical gradient scale length, their dynamics through the modification of the velocity field, and their characteristics for example through the modification of the parallel connection length. In the present seminar we present an overview of the experimental observations on these processes as obtained in the edge region of RFX-mod experiment, operated both as a Reversed Field Pinch and as a tokamak. We will also provide comparison with observations obtained in other devices.
The way a 3D field interacts with plasma turbulence is presently a matter of active research. Indeed it is well known that fluctuations carry a substantial fraction of particle and energy transport, in particular in the periphery of confined plasma. In this region transport is dominated by the presence of coherent structure/blobs, i.e. fluctuations localized in space and time which carry energy and particles through their convective motion and/or their mutual interaction. These structures exhibit the feature of filaments elongated in the direction of the magnetic field: the presence of a non axisymmetric magnetic field is believed to modify their properties acting on their source of free energy through the modulation of typical gradient scale length, their dynamics through the modification of the velocity field, and their characteristics for example through the modification of the parallel connection length. In the present seminar we present an overview of the experimental observations on these processes as obtained in the edge region of RFX-mod experiment, operated both as a Reversed Field Pinch and as a tokamak. We will also provide comparison with observations obtained in other devices.
Practical information
- Informed public
- Free
Organizer
- Prof. P. Ricci, CRPP
Contact
- Prof. P. Ricci, CRPP