Pinch (plasma Physics)

Pinch (plasma Physics)

A pinch is the compression of an electrically conducting filament by magnetic forces. The conductor is usually a plasma, but could also be a solid or liquid metal. In a z-pinch, the current is axial (in the z direction in a cylindrical coordinate system) and the magnetic field azimuthal; in a theta-pinch, the current is azimuthal (in the theta direction in cylindrical coordinates) and the magnetic field is axial. The phenomenon may also be referred to as a "Bennett pinch" (after Willard Harrison Bennett), "electromagnetic pinch", "magnetic pinch", "pinch effect" or "plasma pinch".

Pinches occur naturally in electrical discharges such as lightning bolts, the aurora, current sheets, and solar flares. They are also produced in the laboratory, primarily for research into fusion power, but also by hobbyists (crushing aluminium cans).