A thermonuclear reaction is a nuclear fusion reaction in which the interacting particles or nuclei possess sufficient kinetic energy, as a result of their thermal agitation, to initiate and sustain the process. Controlled thermonuclear reactions attempt to make use of fusion reactions in deuterium and tritium gas, at a temperature in the range 5 × 108 to 5 × 109 °C, for the purpose of generating electrical energy. The central problem in achieving this is containment, i.e. separating the plasma (or high temperature ionized gas) from the walls of the containing vessel. In general, the plasma may be contained either by the use of externally applied magnetic fields, or by the magnetic fields produced by currents flowing in the plasma itself (see pinch effect). The nature and instabilities of these magnetic fields is the subject of contemporary research.