Editing Fusion power (section)

=== Magnetic confinement ===
{{Main|Magnetic confinement fusion}}
* [[Tokamak]]: the most well-developed and well-funded approach. This method drives hot plasma around in a magnetically confined [[torus]], with an internal current. When completed, ITER will become the world's largest tokamak. As of September 2018 an estimated 226 experimental tokamaks were either planned, decommissioned or operating (50) worldwide.<ref>{{Cite web|title=All-the-Worlds-Tokamaks|url=http://www.tokamak.info/|access-date=October 11, 2020|website=www.tokamak.info}}</ref>
* [[Spherical tokamak]]: also known as spherical torus. A variation on the tokamak with a spherical shape.
* [[Stellarator]]: Twisted rings of hot plasma. The stellarator attempts to create a natural twisted plasma path, using external magnets. Stellarators were developed by [[Lyman Spitzer]] in 1950 and evolved into four designs: Torsatron, Heliotron, Heliac and Helias. One example is [[Wendelstein 7-X]], a German device. It is the world's largest stellarator.<ref>{{Cite web|title=The first plasma: the Wendelstein 7-X fusion device is now in operation|url=https://www.ipp.mpg.de/3984226/12_15|access-date=October 11, 2020|website=www.ipp.mpg.de|language=en}}</ref>
* Internal rings: Stellarators create a twisted plasma using external magnets, while tokamaks do so using a current induced in the plasma. Several classes of designs provide this twist using conductors inside the plasma. Early calculations showed that collisions between the plasma and the supports for the conductors would remove energy faster than fusion reactions could replace it. Modern variations, including the [[Levitated dipole|Levitated Dipole Experiment (LDX)]], use a solid superconducting torus that is magnetically levitated inside the reactor chamber.<ref>{{Cite web|last=Chandler|first=David|title=MIT tests unique approach to fusion power|url=https://news.mit.edu/2008/ldx-tt0319|access-date=October 11, 2020|website=MIT News {{!}} Massachusetts Institute of Technology|date=March 19, 2008 |language=en}}</ref>
* [[Magnetic mirror]]: Developed by [[Richard F. Post]] and teams at Lawrence Livermore National Laboratory ([[LLNL]]) in the 1960s.<ref name="Post 99–111">{{Citation|last=Post|first=R. F.|title=Mirror systems: fuel cycles, loss reduction and energy recovery|date=January 1, 1970|url=https://www.icevirtuallibrary.com/doi/abs/10.1680/nfr.44661.0007|work=Nuclear fusion reactors|pages=99–111|series=Conference Proceedings|publisher=Thomas Telford Publishing|doi=10.1680/nfr.44661|isbn=978-0727744661|access-date=October 11, 2020}}</ref> Magnetic mirrors reflect plasma back and forth in a line. Variations included the [[Tandem Mirror Experiment|Tandem Mirror]], magnetic bottle and the [[biconic cusp]].<ref>{{Cite book|last1=Berowitz|first1=J. L |title=Proceedings of the second United Nations International Conference on the Peaceful Uses of Atomic Energy |volume=31|last2=Grad|first2=H.|last3=Rubin|first3=H.|date=1958|publisher=United Nations|location=Geneva|language=en|oclc=840480538}}</ref> A series of mirror machines were built by the US government in the 1970s and 1980s, principally at LLNL.<ref>{{cite journal | last1=Bagryansky | first1=P. A. | last2=Shalashov | first2=A. G. | last3=Gospodchikov | first3=E. D. | last4=Lizunov | first4=A. A. | last5=Maximov | first5=V. V. | last6=Prikhodko | first6=V. V. | last7=Soldatkina | first7=E. I. | last8=Solomakhin | first8=A. L. | last9=Yakovlev | first9=D. V. | title=Threefold Increase of the Bulk Electron Temperature of Plasma Discharges in a Magnetic Mirror Device | journal=Physical Review Letters | volume=114 | issue=20 | date=May 18, 2015 | issn=0031-9007 | doi=10.1103/physrevlett.114.205001 | pmid=26047233 | page=205001| arxiv=1411.6288 | bibcode=2015PhRvL.114t5001B | s2cid=118484958 }}</ref> However, calculations in the 1970s estimated it was unlikely these would ever be commercially useful.
* [[Bumpy torus]]: A number of magnetic mirrors are arranged end-to-end in a toroidal ring. Any fuel ions that leak out of one are confined in a neighboring mirror, permitting the plasma pressure to be raised arbitrarily high without loss. An experimental facility, the ELMO Bumpy Torus or EBT was built and tested at [[Oak Ridge National Laboratory]] (ORNL) in the 1970s.
* [[Field-reversed configuration]]: This device traps plasma in a self-organized quasi-stable structure; where the particle motion makes an internal magnetic field which then traps itself.<ref name="Freidberg2007">{{cite book|first=Jeffrey P. |last=Freidberg|title=Plasma Physics and Fusion Energy|url={{google books |plainurl=y |id=ZGU-ngEACAAJ}}|date= 2007|publisher=Cambridge University Press|isbn=978-0521851077}}</ref>
* [[Spheromak]]: Similar to a field-reversed configuration, a semi-stable plasma structure made by using the plasmas' self-generated magnetic field. A spheromak has both toroidal and poloidal fields, while a field-reversed configuration has no toroidal field.<ref>{{cite book |title=Magnetic Fusion Technology |publisher=Springer London |year=2013 |isbn=978-1447155553 |editor-last=Dolan |editor-first=Thomas J. |series=Lecture Notes in Energy |volume=19 |location=London, England |pages=30–40 |language=en |doi=10.1007/978-1-4471-5556-0 |issn=2195-1284 }}</ref>
* [[Dynomak]] is a spheromak that is formed and sustained using continuous [[magnetic flux]] injection.<ref>D. A. Sutherland, T. R. Jarboe et al., "The dynomak: An advanced spheromak reactor concept with imposed-dynamo current drive and next-generation nuclear power technologies", Fusion Engineering and Design, Volume 89, Issue 4, April 2014, pp. 412–425.</ref><ref>Jarboe, T. R., et al. "Spheromak formation by steady inductive helicity injection." Physical Review Letters 97.11 (2006): 115003</ref><ref>Jarboe, T. R., et al. "Recent results from the HIT-SI experiment." Nuclear Fusion 51.6 (2011): 063029</ref> 
* [[Reversed field pinch]]: Here the plasma moves inside a ring. It has an internal magnetic field. Moving out from the center of this ring, the magnetic field reverses direction.