Editing Fusor (section)

=== Net power ===

At such conditions, the atoms are ionized and make a [[plasma (physics)|plasma]]. The energy generated by fusion, inside a hot plasma cloud can be found with the following equation.<ref name = "Lawson">John Lawson, "Some Criteria for a Power producing thermonuclear reactor", Atomic Energy Research Establishment, Hanvell, Berks, 2 November 1956.</ref>

: <math>P_\text{fusion} = n_A n_B \langle \sigma v_{A,B} \rangle E_\text{fusion},</math>
where
: <math>P_\text{fusion}</math> is the fusion power density (energy per time per volume),
: ''n'' is the number density of species A or B (particles per volume),
: <math>\langle \sigma v_{A,B} \rangle</math> is the product of the collision cross-section ''σ'' (which depends on the relative velocity) and the relative velocity ''v'' of the two species, averaged over all the particle velocities in the system,
: <math>E_\text{fusion}</math> is the energy released by a single fusion reaction.

This equation shows that energy varies with the temperature, density, speed of collision, and fuel used. To reach net power, fusion reactions have to occur fast enough to make up for energy losses. Any power plant using fusion will hold in this hot cloud. Plasma clouds lose energy through [[Thermal conduction|conduction]] and [[radiation]].<ref name = "Lawson"/>  Conduction is when [[ion]]s, [[electron]]s or [[neutral particle|neutrals]] touch a surface and leak out. Energy is lost with the particle. Radiation is when energy leaves the cloud as light. Radiation increases as the temperature rises. To get net power from fusion it's necessary to overcome these losses. This leads to an equation for power output.

: <math>P_\text{out} = \eta_\text{capture} (P_\text{fusion} - P_\text{conduction} - P_\text{radiation}).</math>
where:
: ''η'' is the efficiency,
: <math>P_\text{conduction}</math> is the power of conduction losses as energy-laden mass leaves,
: <math>P_\text{radiation}</math> is the power of radiation losses as energy leaves as light,
: <math>P_\text{out}</math> is the net power from fusion.

John Lawson used this equation to estimate some conditions for net power<ref name = "Lawson"/> based on a [[Maxwell–Boltzmann distribution|Maxwellian]] cloud.<ref name = "Lawson"/>  This became the [[Lawson criterion]]. Fusors typically suffer from [[Thermal conduction|conduction]] losses due to the wire cage being in the path of the recirculating plasma.