Editing Inertial electrostatic confinement (section)

{{short description|Fusion power research concept}}
[[File:Deuterium Ionized.JPG|thumb|right|275px|A [[fusor]], exhibiting nuclear fusion in '''star''' mode]]

'''Inertial electrostatic confinement''', or '''IEC''', is a class of [[fusion power]] devices that use [[electric field]]s to confine the [[plasma (physics)|plasma]] rather than the more common approach using [[magnetic field]]s found in [[magnetic confinement fusion]] (MCF) designs. Most IEC devices directly accelerate their fuel to fusion conditions, thereby avoiding energy losses seen during the longer heating stages of MCF devices. In theory, this makes them more suitable for using alternative [[aneutronic fusion]] fuels, which offer a number of major practical benefits and makes IEC devices one of the more widely studied approaches to fusion.

IEC devices were the very first [[fusion power| fusion]] products to reach the commercial market in 2000, as neutron generators.<ref>{{Cite book| edition = 1st| publisher = Springer| isbn = 978-3-031-22905-3| last1 = Moynihan| first1 = Matthew| last2 = Bortz| first2 = Alfred B.| title = Fusion's Promise: How Technological Breakthroughs in Nuclear Fusion Can Conquer Climate Change on Earth| date = 2023-03-25}}</ref> A company called NSD-Gradel developed a compact IEC device that fused ions and created neutrons and sold the product for several hundred thousand dollars.  

As the negatively charged [[electron]]s and positively charged [[ion]]s in the plasma move in different directions in an electric field, the field has to be arranged in some fashion so that the two particles remain close together. Most IEC designs achieve this by pulling the electrons or ions across a potential well, beyond which the potential drops and the particles continue to move due to their [[inertia]]. Fusion occurs in this lower-potential area when ions moving in different directions collide. Because the motion provided by the field creates the energy levels needed for fusion, not random collisions with the rest of the fuel, the bulk of the plasma does not have to be hot and the systems as a whole work at much lower temperatures and energy levels than MCF devices.

One of the simpler IEC devices is the [[fusor]], which consists of two concentric metal wire spherical grids. When the grids are charged to a high [[voltage]], the fuel gas ionizes. The field between the two then accelerates the fuel inward, and when it passes the inner grid the field drops and the ions continue inward toward the center. If they impact with another ion they may undergo fusion. If they do not, they travel out of the reaction area into the charged area again, where they are re-accelerated inward. Overall the physical process is similar to the [[colliding beam fusion]], although beam devices are linear instead of spherical. Other IEC designs, like the [[polywell]], differ largely in the arrangement of the fields used to create the potential well.

A number of detailed theoretical studies have pointed out that the IEC approach is subject to a number of energy loss mechanisms that are not present if the fuel is evenly heated, or [[Maxwell–Boltzmann distribution|"Maxwellian"]]. These loss mechanisms appear to be greater than the rate of fusion in such devices, meaning they can never reach [[fusion breakeven]] and thus be used for power production. These mechanisms are more powerful when the [[atomic mass]] of the fuel increases, which suggests IEC also does not have any advantage with aneutronic fuels. Whether these critiques apply to specific IEC devices remains highly contentious.