The Lawson Criterion is a concept in nuclear fusion physics that describes the necessary conditions for fusion to occur. The spelling of Lawson is pronounced /ˈlɔːsən/ in IPA phonetic transcription. The first syllable sounds like "law," the second syllable sounds like "son." The word is spelled with an "aw" instead of an "o" because it comes from a surname. The spelling of Criterion is pronounced /kraɪˈtɪərɪən/ in IPA phonetic transcription. The first syllable sounds like "cry," the second syllable sounds like "tear," and the final syllable sounds like "ian."
The Lawson criterion refers to a fundamental principle and measure for achieving controlled nuclear fusion in a fusion reactor. It defines the minimum conditions required to achieve a sustainable fusion reaction by balancing the rate of energy production and loss. The Lawson criterion is named after John D. Lawson, who formulated it in 1955.
The criterion states that in order to achieve a self-sustaining fusion reaction, the product of the plasma density (n), the plasma confinement time (τ), and the plasma temperature (T) must exceed a specific value. Mathematically, it can be expressed as nτE ≥ β, where E is the energy required to initiate fusion reactions, and β is a dimensionless constant that represents the efficiency of the reactor. The Lawson criterion emphasizes the crucial role of plasma density and confinement time in achieving fusion.
A high plasma density is required to increase the probability of fusion reactions occurring. Additionally, the plasma must be sufficiently confined for a long enough time to allow fusion to produce more energy than is consumed. Balancing these parameters is the key to achieving net energy gain in a fusion reactor. Scientists and engineers use the Lawson criterion as a theoretical guideline to evaluate and compare the performance and feasibility of different fusion reactor designs.
Overall, the Lawson criterion is an important concept in the field of nuclear fusion research, guiding the development of technologies and experimental setups to achieve efficient and sustainable fusion reactions.