Perhapsatron

The Perhapsatron was an early fusion power device based on the pinch concept in the 1950s. Dreamt up by James (Jim) Tuck while working at Los Alamos National Laboratory (LANL), he named the device whimsically on the off chance that it might be able to create fusion reactions.

The first example was built in the winter of 1952/53, and it quickly demonstrated a series of instabilities in the plasma that plagued the pinch concept. A series of modifications followed which attempted to correct these problems, leading to the ultimate "S-4" model. However, none of these proved fruitful.

Scientists at Los Alamos National Laboratory had a long history of studying nuclear fusion, and by 1946 they had already calculated that a steady-state plasma would have to be heated to 100 million degrees Celsius (180 million degrees Fahrenheit) in order to "ignite" and release net energy. This was of vital interest in the nuclear bomb establishment, where the use of a small atomic bomb "trigger" was used to provide the required temperatures.

Capturing that energy on a smaller industrial scale would not be easy - plasma at that temperature would melt any physical container. As plasma is electrically conductive it was obvious that it could be contained magnetically, but the proper arrangement of the fields was not obvious -- Enrico Fermi pointed out that a simple toroid would cause the fuel to drift out of the "bottle". Several arrangements were eventually studied over time, notably the stellarator concept developed around 1950.

An alternate approach was the "pinch" concept, developed in the United Kingdom. Unlike the magnetic bottle approaches, in a pinch device, the required magnetic field was created by the plasma itself. Since the plasma is electrically conductive, if one were to run a current through the plasma, it would create an induced magnetic field. This field, through the Lorentz force, will act to compress the conductor. In the case of a plasma, the force would collapse it into a thin filament, "pinching" it down. Since the current had to be very large, pinch devices made no attempt to confine the plasmas for extended periods. They would attempt to reach fusion conditions quickly and then extract power from the resulting hot products.

...
Wikipedia