Z-pinch

This places a limit on the product of confinement time and magnetic field, for any given source of power.

The announcement of the Huemul Project in early 1951 led to fusion efforts around the world, notably in the UK and in the US (see Perhapsatron, a z-pinch machine at LANL).

Small experiments were built at labs as various practical issues were addressed, but all of these machines demonstrated unexpected instabilities of the plasma that would cause it to hit the walls of the container vessel.

The result was that the formerly straight magnetic field was twisted into a helix, which the particles followed as they traveled around the tube driven by the current.

At the time, almost all fusion research was classified, so progress on ZETA was generally unknown outside the labs working on it.

Despite the researchers' reservations, their results were released with great fanfare as the first successful step on the path to commercial fusion energy.

A concept of Z-pinch fusion propulsion system was developed through collaboration between NASA and private companies.

[1] The energy released by the Z-pinch effect would accelerate lithium propellant to a high speed, resulting in a specific impulse value of 19400 s and thrust of 38 kN.

[2] Although it remained relatively unknown for years, Soviet scientists used the pinch concept to develop the tokamak device.

This reduced the instabilities due to the large currents in the plasma, and led to great improvements in stability.

Plasma temperatures of 1–2 keV (12–24 million °C) and densities of approximately 1017 cm−3 with 0.3 cm pinch radii were measured.