The first use of the pinch effect was to confine the plasma in a cylinder. This, however, could not be made to work. The situation was too unstable. The plasma was held momentarily, then writhed and broke up.
Plasma in a magnetic field.
Enormous machines and complex equipment, such as the Scyllac machine shown above, are required for nuclear fusion research.
Attempts were made to remove the instability. The field was so designed as to be stronger at the ends of the cylinder than elsewhere. The particles in the plasma would stream toward one end or another and would then bounce back producing a so-called “magnetic mirror”.
In 1951 the American physicist Lyman Spitzer, Jr. (1914- ) had worked out the theoretical benefits to be derived from a container twisted into a figure-eight shape. Eventually, such devices were built and called “stellarators” from the Latin word for “star”, because it was hoped that it would produce the conditions that would allow the sort of fusion reactions that went on in stars.
All through the 1950s and 1960s, physicists have been slowly inching toward their goal, reaching higher and higher temperatures and holding them for longer and longer periods in denser and denser gases.
In 1969 the Soviet Union used a device called “Tokamak-3” (a Russian abbreviation for their phrase for “electric-magnetic”) to keep a supply of hydrogen-2, a millionth as dense as air, in place while heating it to tens of millions of degrees for a hundredth of a second.
A little denser, a little hotter, a little longer—and controlled fusion might become possible.[5]