"On the one hand, there are the approaches that lead to stationary thermonuclear reactions, and on the other hand, those that are based on the idea of utilizing an instantaneous temperature rise in transient processes of very brief duration. However, irrespective of the way the investigation is carried out, there is one problem that is inevitably encountered; namely, the insulation of the plasma, which is heated to a high temperature, from the walls of the vessel in which it is confined, In other words, a means must be found to keep the fast particles within the plasma over a period sufficient for the particles to have a good chance to react with each other."