Ever since it was postulated in 1939 that stars obtain their energy from fusion reactions, continuous attempts have been made to harness this fusion, the main source of energy in the universe, in a controlled manner. However, it was realized in 1957 that to use fusion to produce electricity on Earth, even with the most reasonable fuel, a mixture of 50% deuterium and 50% tritium, the material would have to be heated to temperatures equivalent to at least 10 keV (approximately 10⁸ K). The problem is how to isolate enough fuel (approximately 1–2 × 10²⁰ particles/m³) at such extreme temperatures (1–2 × 10⁸ K) from the surrounding environment for enough time (approximately 2–3 s) to allow a sufficient number of reactions to occur and make the overall energy production process efficient.