"Experimental investigation of filamentary current structures associated with blobs in TORPEX plasmas"
Event details
| Date | 18.03.2013 |
| Hour | 10:30 › 11:30 |
| Speaker | Fabio Rivaz, étudiant EPFL (master) |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
Many studies have shown that a big amount of the turbulent transport appearing in the SOL of plasma devices is due to the emergence of filamentary coherent structures (blobs) carrying particles toward the walls. To model the dynamic of this turbulent phenomenon, many closure schemes have been proposed. All the schemes are derived by the fundamental equation of charge conservation ∇ ~ J = 0.
Assuming that the filaments of plasma are intercepted at their ends by a perpendicular (referred to magnetic field lines) conducting limiter, the so-called "Sheath-limited model" is obtained, which allows analyzing the currents associated with blobs. From this model, combined with some simple approximations, follows the vorticity equation. This equation states an equilibrium between the four currents appearing in the blobs: the current induced by the charged-particle drifts is compensated by the emergence of others three currents, namely the ion polarization current, the parallel current to the sheath and the current due to the friction between ions and neutrals.
Previous experimental works have shown that in plasmas of hydrogen the current induced by the charged-particle drifts is mainly compensated by the parallel current to the sheath. Thus, the dynamic of blobs is derived from the combination of this result with the assumption of a linear behavior of the filamentary current structures along the magnetic field lines: the speed-versus-size scaling law equation is obtained, which states a velocity of blobs proportional to a
Assuming that the filaments of plasma are intercepted at their ends by a perpendicular (referred to magnetic field lines) conducting limiter, the so-called "Sheath-limited model" is obtained, which allows analyzing the currents associated with blobs. From this model, combined with some simple approximations, follows the vorticity equation. This equation states an equilibrium between the four currents appearing in the blobs: the current induced by the charged-particle drifts is compensated by the emergence of others three currents, namely the ion polarization current, the parallel current to the sheath and the current due to the friction between ions and neutrals.
Previous experimental works have shown that in plasmas of hydrogen the current induced by the charged-particle drifts is mainly compensated by the parallel current to the sheath. Thus, the dynamic of blobs is derived from the combination of this result with the assumption of a linear behavior of the filamentary current structures along the magnetic field lines: the speed-versus-size scaling law equation is obtained, which states a velocity of blobs proportional to a
Practical information
- Informed public
- Free
Organizer
- Prof. P. Ricci
Contact
- Prof. P. Ricci