Pinch (plasma physics)

Pinch phenomena
Lightning discharge bolts showing electromagnetically pinched plasma filaments
A 1905 study of pinches, where electric lightning was used to create a Z-pinch inside a metal tube.
A current-driven toroidal Z-pinch in a krypton plasma

A pinch (or: Bennett pinch (after Willard Harrison Bennett), electromagnetic pinch, magnetic pinch, pinch effect, or plasma pinch.) is the compression of an electrically conducting filament by magnetic forces, or a device that does such. The conductor is usually a plasma, but could also be a solid or liquid metal. Pinches were the first type of device used for experiments in controlled nuclear fusion power.

Pinches occur naturally in electrical discharges such as lightning bolts, planetary auroras, current sheets, and solar flares.