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 that was declassified and published in 1957. As originally formulated, the Lawson criterion gives a minimum required value for the product of the plasma (electron) density ne and the "energy confinement time" 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. Energy balance The central concept of the Lawson criterion is an examination of the energy balance for any fusion power plant using a hot plasma. This is shown below: Net power = Efficiency × (Fusion − Radiation loss − Conduction loss) Net power is the excess power beyond that needed internally for the process to proceed in any fusion power plant. Efficiency is how much energy is needed to drive the device and how well it collects energy from the reactions. Fusion is rate of energy generated by the fusion reactions. Radiation loss is the energy lost as light (including X-rays) leaving the plasma. Conduction loss is the energy lost as particles leave the plasma, carrying away energy. Lawson calculated the fusion rate by assuming that the fusion reactor contains a hot plasma cloud which has a Gaussian curve of individual particle energies, a Maxwell–Boltzmann distribution characterized by the plasma's temperature. Based on that assumption, he estimated the first term, the fusion energy being produced, using the volumetric fusion equation. Fusion = Number density of fuel A × Number density of fuel B × Cross section(Temperature) × Energy per reaction Fusion is the rate of fusion