History of the Z-Pinch

The pinch was first investigated by W.H. Bennet in 1934. The pinch effect occurs when magnetic pressure exceeds the particle pressure of the plasma. The magnetic feld may diffuse the plasma, or the plasma boundary can increase the particle pressure. To achieve this effect, frozen hydrogen fibers were put between two electrodes to form plasma. This was given up because it was very unstable. The plasma column made sausage pinches in a few places, where the plasma broke off, and the current was disrupted. When the plasma broke off, it cooled down. In the University of Washington ZaP project, an axial flow is generated in a coaxial gun, which stablizes this process. This works because as you squeeze the magnetic field farther, the magnetic field increases.

[Current Carrying Plasma Column]

Current Carrying Plasma Column

This schematic illustrates the plasma pinch effect. Plasma current J creates a magnetic field B, that exerts a radially inward force acting against the plasma pressure nkT. This is a physical explanation of what occurs in the axial gun.
[Successful Plasma Flow Schematic]

Successful Plasma Flow

This schematic illustrates actual plasma flow. This prevents instability. You still want a pinch, but you want it to exist in uniformity because that brings the plasma to fusion conditions.