Tearing mode stabilization in tokamaks with lower hybrid waves

Tearing Mode Stabilization in Tokamaks with Lower Hybrid Waves

The possibility of using lower hybrid (LH) waves as a source of localized current for the control of MHD instabilities is investigated. A toroidal ray tracing code is used to define the requirements on the launched wave spectrum, in order to drive currents mostly localized inside the magnetic islands. Issues such as the radial diffusion of the non-inductive current, the impact of the radial pro...

Complete stabilization of neoclassical tearing modes with lower hybrid current drive on COMPASS-D. RF teams.

Lower hybrid current drive (LHCD) with modest powers ( approximately 10% of the total power input) has been used for the first time to completely stabilize performance limiting neoclassical tearing modes in many COMPASS-D tokamak discharges. The stabilizing effect in these experiments is consistent with a reduction in the free energy available in the current profile to drive tearing modes (i.e....

Electromagnetic particle simulation of the linear mode conversion and the nonlinear parametric decay instability of lower hybrid waves in tokamaks

In plasma simulations where the speed of light times a characteristic length is at a much higher frequency than the relevant parameters in the system, such as the plasma frequency, implicit methods begin to play an important role in generating e cient solutions in these multi-scale problems. Under conditions of scale separation, one can rescale Maxwell’s equations in such a way as to give a mag...

Time-dependent Simulations of Neoclassical Tearing Mode Stabilization in TCV

Full wave simulations of lower hybrid wave propagation in tokamaks

Lower hybrid (LH) waves have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons at (2.5−−3)× vte, where vte ≡ (2Te/me) is the electron thermal speed. Consequently these waves are well-suited to driving current in the plasma periphery where the electron temperature is lower, making LH current drive (LHCD) a promising technique for off-axis...