Lawson criterion

The Lawson criterion is a figure of merit used in nuclear fusion research. It compares the rate of energy being generated by fusion reactions within the fusion fuel to the rate of energy losses to the environment. When the rate of production is higher than the rate of loss, the system will produce net energy. If enough of that energy is captured by the fuel, the system will become self-sustaining and is said to be ignited.

The concept was first developed by John D. Lawson in a classified 1955 paper^[1] that was declassified and published in 1957.^[2] As originally formulated, the Lawson criterion gives a minimum required value for the product of the plasma (electron) density n_e and the "energy confinement time" ${\displaystyle \tau _{E}}$ that leads to net energy output.

Later analysis suggested that a more useful figure of merit is the triple product of density, confinement time, and plasma temperature T. The triple product also has a minimum required value, and the name "Lawson criterion" may refer to this value.

On August 8, 2021, researchers at Lawrence Livermore National Laboratory's National Ignition Facility in California confirmed to have produced the first-ever successful ignition of a nuclear fusion reaction surpassing the Lawson's criteria in the experiment.^[3][4]