Kink instability
A kink instability (also known as a kink oscillation or kink mode) is a current-driven plasma instability characterized by transverse displacements of a plasma column's cross-section from its center of mass without any change in the characteristics of the plasma. It typically develops in a thin plasma column carrying a strong axial current which exceeds the Kruskal–Shafranov limit[1][2][3] and is sometimes known as the Kruskal–Shafranov (kink) instability,[4][5] named after Martin David Kruskal and Vitaly Shafranov.
The kink instability was first widely explored in fusion power machines with Z-pinch configurations in the 1950s.[6] It is one of the common magnetohydrodynamic instability modes which can develop in a pinch plasma and is sometimes referred to as the mode.[6] (The other is the mode known as the sausage instability.)
If a "kink" begins to develop in a column the magnetic forces on the inside of the kink become larger than those on the outside, which leads to growth of the perturbation.[6][7] As it develops at fixed areas in the plasma, kinks belong to the class of "absolute plasma instabilities", as opposed to convective processes.