Modifying locally the safety profile to improve the confinement of magnetic field lines in tokamak plasmas

D. Constantinescu (1) , Marie-Christine Firpo (2)

1 Department of Applied Mathematics, Association Euratom-MECI
2 LPP - Laboratoire de Physique des Plasmas

Using Hamiltonian models for the magnetic field lines, we propose a methodology to improve their confinement through the creation of transport barriers. A local modification of the safety profile creating a low-shear zone is shown to be sufficient to locally enhance drastically the regularity of the magnetic field lines without requesting a reversed shear. The optimal benefits of low-shear are obtained when the value q0 of the safety profile in the low-shear zone is sufficiently far from the main resonance values m/n with low m and n, in the case of large enough values of those (m, n) mode amplitudes. A practical implementation in tokamak plasmas should involve electron cyclotron current drive to locally modify the magnetic shear.

Mots clés: fusion; magnetic confinement

Domaines: Physique des plasmas [physics.plasm-ph]

D. Constantinescu, Marie-Christine Firpo. Modifying locally the safety profile to improve the confinement of magnetic field lines in tokamak plasmas. Nuclear Fusion, 2012, 52 (5), pp.054006. ⟨10.1088/0029-5515/52/5/054006⟩. ⟨hal-00698991⟩