In fusion power research, the Z-pinch (zeta pinch) is a type of plasma confinement system that uses an electric current in the plasma to generate a magnetic field that compresses it (see pinch). These systems were originally referred to simply as pinch or Bennett pinch (after Willard Harrison Bennett), but the introduction of the θ-pinch (theta pinch) concept led to the need for clearer, more precise terminology.
The name refers to the direction of the current in the devices, the Z-axis on a Cartesian three-dimensional graph. Any machine that causes a pinch effect due to current running in that direction is correctly referred to as a Z-pinch system, and this encompasses a wide variety of devices used for an equally wide variety of purposes. Early uses focused on fusion research in donut-shaped tubes with the Z-axis running down the inside of the tube, while modern devices are generally cylindrical and used to generate high-intensity x-ray sources for the study of nuclear weapons and other roles. It is one of the first approaches to fusion power devices, along with the stellarator and magnetic mirror.