Review of Controlled Thermonuclear Research at A.E.I.

At temperatures of several hundred million degrees, in deuterium, the energy generated by nuclear re-actions will exceed the radiation loss. This fact suggested to one of us (G.P.T.), in 1946, that useful power might be generated from such reactions, pro-vided that the loss of energy to the walls could be sufficiently reduced by magnetic fields. Experiments were begun at Imperial College, London, in February 1947, to produce very large currents in a low-pressure gas discharge. The containment of the gas was to be achieved by the pinch effect and a toroidal discharge tube was used to eliminate end losses. Currents in the range 1 x 104-2 x 104 amp were induced in the gas by discharging a condenser of maximum energy 400 joules through a primary winding coupled with the gas.1 These experiments were the first to demonstrate a marked pinch effect in a gas discharge, although inertial effects caused the contracting discharge to overswing and expand again, followed by further contractions and expansions.2 In order to achieve temperatures of several million degrees and demonstrate a thermonuclear reaction it was clear from the Bennett3 relation, 2NkT =72, that currents of the order 105 amp were required. (N is the total number of particles per unit length of the discharge, k Boltzmann's constant, T the tempera-ture and / the current.) When, however, the condenser energy was increased in 1950 to 18,000 joules, serious crazing and evaporation of the small Pyrex glass dis-charge tubes occurred and it became necessary to develop superior materials to contain the large currents. At this juncture thermonuclear research was made secret by the Government and, because of the un-desirabüity of conducting secret research at a university, the staff and apparatus were moved to th