Princeton tokamak exceeds supposed density limit

A novel variation on the Russian tokamak has dispelled some of the reverence for traditional tokamak technology while achieving a modest advancement of plasma parameters. The experiment, done with the Adiabatic Toroidal Compressor (ATC) at Princeton, eliminates the copper “stabilizing shell” surrounding the plasma, which was believed to play a vital role in assuring magnetohydrodynamic stability. Furthermore it shows that heating by compression can take place in a tokamak plasma, and it indicates that there is no limit to the density that can be reached in a stable tokamak plasma. Results were reported at the November meeting of the APS Plasma Physics Division in Monterey, California and in the 27 November issue of Physical Review Letters (29, 1495, 1972).