Using non-axisymmetric scrape-off layer perturbations to control the tokamak edge plasma
Event details
| Date | 29.05.2012 |
| Hour | 09:30 › 10:30 |
| Speaker | Dr Ilon Joseph, Lawrence Livermore National Laboratory, USA |
| Location |
PPB.019
|
| Category | Conferences - Seminars |
Tokamak fusion reactors require the ability to control the power exhausted to the divertor target plates, including both the time-averaged heat loads and the impulsive fluxes that accompany edge-localized modes. Driving toroidally-asymmetric perturbations through the scrape-off layer (SOL) plasma can be used to broaden the SOL by generating potentials that drive radial convection [1] and to control the edge pedestal pressure gradient by generating currents that drive external magnetic perturbations [2]. The generation of additional convective transport via steady-state convective cells or increased turbulence drive requires that the electric potential perturbations exceed a threshold in amplitude that is optimized at higher radial and toroidal mode number. The generation of a coherent resonant magnetic perturbation requires a coherent SOL current along the separatrix and can be optimized by choosing the appropriate width and phasing of the biasing region at the target plate. Longer toroidal wavelength modes produce a larger effect because they are not sheared as strongly by the magnetic X-point. Generation of the necessary currents is challenging due to the possibly substantial power requirements and the possible need for internal insulators. Reactor-relevant passive current-drive mechanisms rely on controlling the thermo-electric potential in a toroidally asymmetric fashion near the target plate. The technique of puffing and pumping of neutral gas in order to control the target plate electron temperature is analyzed using the UEDGE code.
*Prepared for US DOE by LLNL under Contract # DE-AC52- 07NA27344.
[1] R. H. Cohen and D. D. Ryutov. Nucl. Fusion 37, 621 (1997).
[2] I. Joseph, R. H. Cohen and D. D. Ryutov, Phys. Plasmas 16, 052510 (2009).
*Prepared for US DOE by LLNL under Contract # DE-AC52- 07NA27344.
[1] R. H. Cohen and D. D. Ryutov. Nucl. Fusion 37, 621 (1997).
[2] I. Joseph, R. H. Cohen and D. D. Ryutov, Phys. Plasmas 16, 052510 (2009).
Practical information
- Expert
- Free
Organizer
- CRPP
Contact
- Ricci Paolo