Magnetic-confinement fusion

An Erratum to this article was published on 30 June 2016

This article has been updated


Our modern society requires environmentally friendly solutions for energy production. Energy can be released not only from the fission of heavy nuclei but also from the fusion of light nuclei. Nuclear fusion is an important option for a clean and safe solution for our long-term energy needs. The extremely high temperatures required for the fusion reaction are routinely realized in several magnetic-fusion machines. Since the early 1990s, up to 16 MW of fusion power has been released in pulses of a few seconds, corresponding to a power multiplication close to break-even. Our understanding of the very complex behaviour of a magnetized plasma at temperatures between 150 and 200 million °C surrounded by cold walls has also advanced substantially. This steady progress has resulted in the construction of ITER, a fusion device with a planned fusion power output of 500 MW in pulses of 400 s. ITER should provide answers to remaining important questions on the integration of physics and technology, through a full-size demonstration of a tenfold power multiplication, and on nuclear safety aspects. Here we review the basic physics underlying magnetic fusion: past achievements, present efforts and the prospects for future production of electrical energy. We also discuss questions related to the safety, waste management and decommissioning of a future fusion power plant.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Particle trajectory in a corkscrew-type magnetic field.
Figure 2: Tokamak configuration and magnetic surfaces.
Figure 3: W7-X optimized stellarator configuration.
Figure 4: Magnetic islands.
Figure 5: Edge-localized mode (ELM) instability.
Figure 6: Limiter and divertor configurations.
Figure 7: Deuterium–tritium fusion records.

Change history

  • 16 June 2016

    In the version of this Review Article originally published, it was not acknowledged that Fig. 3a is courtesy of C. Brandt, IPP. This has been corrected in the online versions 16 June 2016.


  1. 1

    Rebut, P.-H. et al. The JET preliminary tritium experiment. Plasma Phys. Control. Fusion 34, 1749–1758 (1992).

    ADS  Google Scholar 

  2. 2

    Giruzzi, G. et al. Modelling of pulsed and steady-state DEMO scenarios. Nucl. Fusion 55, 073002 (2015).

    ADS  Google Scholar 

  3. 3

    Clery, D. A Piece of the Sun. The Quest for Fusion Energy (Overlook Duckworth, 2013).

    Google Scholar 

  4. 4

    Francis, F. C. An Indispensible Truth. How Fusion Power Can Save The Planet (Springer, 2011).

    Google Scholar 

  5. 5

    Dean, S. O. Search for the Ultimate Energy Source: A History of the U.S. Fusion Energy Program (Springer, 2013).

    Google Scholar 

  6. 6

    Mazon, D., Fenzi, C. & Sabot, R. As hot as it gets. Nature Phys. 12, 14–17 (2016).

    ADS  Google Scholar 

  7. 7

    Porkolab, M. RF heating and current drive in magnetically confined plasma: a historical perspective. AIP Conf. Proc. 933, 3 (2007).

    ADS  Google Scholar 

  8. 8

    Lawson, J. D. Some Criteria for a Useful Thermonuclear Reactor (Atomic Energy Research Establishment, 1955).

    Google Scholar 

  9. 9

    Lawson, J. D. Some criteria for a power producing thermonuclear reactor. Proc. Phys. Soc. B 70, 6–10 (1957).

    ADS  Google Scholar 

  10. 10

    Goldston, R. J. Energy confinement scaling in Tokamaks: some implications of recent experiments with Ohmic and strong auxiliary heating. Plasma Phys. Control. Fusion 26, 87–103 (1984).

    ADS  Google Scholar 

  11. 11

    Kaye, S. M. & Goldston, R. J. Global energy confinement scaling for neutral-beam-heated tokamaks. Nucl. Fusion 25, 65–69 (1985).

    Google Scholar 

  12. 12

    Ryter, F. et al. Electron heat transport studies. Plasma Phys. Control. Fusion 48, B453–B463 (2006).

    Google Scholar 

  13. 13

    Wagner, F. et al. Regime of improved confinement and high beta in neutral-beam-heated divertor discharges of the ASDEX tokamak. Phys. Rev. Lett. 49, 1408–1412 (1982).

    ADS  Google Scholar 

  14. 14

    Bickerton, R. J., Connor, J. W. & Taylor, J. B. Diffusion driven plasma currents and bootstrap tokamak. Nature 229, 110–112 (1971).

    ADS  Google Scholar 

  15. 15

    Balescu, R. Transport Processes in Plasmas Vol. 2 (Elsevier, 1988).

    Google Scholar 

  16. 16

    Fasoli, A. et al. Computational challenges in magnetic-confinement fusion physics. Nature Phys 12, 411–423 (2016).

    ADS  Google Scholar 

  17. 17

    Gusakov, E. Z. et al. Anomalous transport and multi-scale drift turbulence dynamics in tokamak ohmic discharge as measured by high resolution diagnostics and modeled by full-f gyrokinetic code. Plasma Phys. Control. Fusion 55, 124034 (2013).

    ADS  Google Scholar 

  18. 18

    Dumont, R. J. et al. Interplay between fast ions and turbulence in magnetic fusion plasmas. Plasma Phys. Control. Fusion 55, 124012 (2013).

    ADS  Google Scholar 

  19. 19

    Pace, D. C. et al. Keeping fusion plasmas hot. Phys. Today 68(10), 34–39 (2015).

    Google Scholar 

  20. 20

    Howard, N. T. et al. Multi-scale gyrokinetic simulation of tokamak plasmas: enhanced heat loss due to cross-scale coupling of plasma turbulence. Nucl. Fusion 56, 014004 (2016).

    ADS  Google Scholar 

  21. 21

    Staebler, G. M. & Groebner, R. J. H-mode transitions and limit cycle oscillations from mean field transport equations. Plasma Phys. Control. Fusion 57, 014025 (2015).

    ADS  Google Scholar 

  22. 22

    Helander, P. Theory of plasma confinement in non-axisymmetric magnetic fields. Rep. Prog. Phys. 77, 087001 (2014).

    ADS  Google Scholar 

  23. 23

    Xanthopoulos, P. et al. Nonlinear gyrokinetic simulations of ion-temperature-gradient turbulence for the optimized Wendelstein 7-X Stellarator. Phys. Rev. Lett. 99, 035002 (2007).

    ADS  Google Scholar 

  24. 24

    Proll, J. H. E. et al. Resilience of quasi-isodynamic stellarators against trapped-particle instabilities. Phys. Rev. Lett. 108, 245002 (2012).

    ADS  Google Scholar 

  25. 25

    Zohm, H. Magnetohydrodynamic Stability of Tokamaks (Wiley, 2015).

    Google Scholar 

  26. 26

    Troyon, F. et al. MHD-Limits to plasma confinement. Plasma Phys. Control. Fusion 26, 209–215 (1984).

    ADS  Google Scholar 

  27. 27

    Greenwald, M. et al. A new look at density limits in tokamaks. Nucl. Fusion 28, 2199–2207 (1988).

    Google Scholar 

  28. 28

    Zohm, H. Edge Localized Modes (ELMs). Plasma Phys. Control. Fusion 38, 105–128 (1996).

    ADS  Google Scholar 

  29. 29

    Igochine, V. (ed.) Active Control of MHD Instabilities in Hot Plasmas (Springer, 2015).

  30. 30

    Peeters, A. G. The bootstrap current and its consequences. Plasma Phys. Control. Fusion 42, B231–B242 (2000).

    ADS  Google Scholar 

  31. 31

    Gorelenkov, N. et al. Energetic particle physics in fusion research in preparation for burning plasma experiments. Nucl. Fusion 54, 125001 (2014).

    ADS  Google Scholar 

  32. 32

    McCracken, G. & Stott, P. Fusion, the Energy of the Universe (Elsevier, 2005).

    Google Scholar 

  33. 33

    Knaster, J., Moeslang, A. & Muroga, T. Materials research for fusion. Nature Phys. 12, 424–434 (2016).

    ADS  Google Scholar 

  34. 34

    Kotschenreuther, M. et al. On heat loading, novel divertors, and fusion reactors. Phys. Plasmas 14, 072502 (2007).

    ADS  MathSciNet  Google Scholar 

  35. 35

    Valanju, P. M. et al. Super-X divertors and high power density fusion devices. Phys. Plasmas 16, 056110 (2009).

    ADS  Google Scholar 

  36. 36

    Ryutov, D. D. Geometrical properties of a snowflake divertor. Phys. Plasmas 14, 064502 (2007).

    ADS  Google Scholar 

  37. 37

    Pericoli, V. et al. Preliminary 2D code simulation of the quasi-snowflake divertor configuration in the FAST tokamak. Fusion Eng. Des. 88, 1671–1681 (2013).

    Google Scholar 

  38. 38

    Ryutov, D. D. et al. A snowflake divertor: a possible solution to the power exhaust problem for tokamaks. Plasma Phys. Control. Fusion 54, 124050 (2012).

    ADS  Google Scholar 

  39. 39

    Ryutov, D. D. & Umansky, M. Divertor with a third-order null of the poloidal field. Phys. Plasmas 20, 092509 (2013).

    ADS  Google Scholar 

  40. 40

    Winter, J. et al. Improved plasma performance in TEXTOR with silicon coated surfaces. Phys. Rev. Lett. 71, 1549–1552 (1993).

    ADS  Google Scholar 

  41. 41

    Gruber, O. et al. Observation of continuous divertor detachment in H-mode discharges in ASDEX Upgrade. Phys. Rev. Lett. 74, 4217–4220 (1995).

    ADS  Google Scholar 

  42. 42

    Messiaen, A. et al. High confinement and high density with stationary plasma energy and strong edge radiation in the TEXTOR-94 tokamak. Phys. Rev. Lett. 77, 2487–2490 (1996).

    ADS  Google Scholar 

  43. 43

    Ongena, J. et al. Experiments with radiative mantle plasmas. Fusion Sci. Technol. 53, 943–952 (2008).

    Google Scholar 

  44. 44

    Umansky, M. V. et al. Analysis of geometric variations in high-power tokamak divertors. Nucl. Fusion 49, 075005 (2009).

    ADS  Google Scholar 

  45. 45

    Kallenbach, A. et al. Impurity seeding for tokamak power exhaust: from present devices via ITER to DEMO. Plasma Phys. Control. Fusion 55, 124041 (2013).

    ADS  Google Scholar 

  46. 46

    Federici, G. et al. Plasma-material interactions in current tokamaks and their implications for next step fusion reactors. Nucl. Fusion 41, 1967–2137 (2001).

    ADS  Google Scholar 

  47. 47

    Greenwald, M. et al. 20 years of research on the Alcator C-Mod tokamak. Phys. Plasmas 21, 110501 (2014).

    ADS  Google Scholar 

  48. 48

    Neu, R. et al. The tungsten divertor experiment at ASDEX Upgrade. Plasma Phys. Control. Fusion 38, A165–A179 (1996).

    ADS  Google Scholar 

  49. 49

    Romanelli, F. et al. Overview of JET results. Nucl. Fusion 55, 104001 (2015).

    ADS  Google Scholar 

  50. 50

    Höhnle, H. et al. Extension of the ECRH operational space with O2 and X3 heating schemes to control tungsten accumulation in ASDEX Upgrade. Nucl. Fusion 51, 083013 (2011).

    ADS  Google Scholar 

  51. 51

    Maisonnier, D. et al. Power plant conceptual studies in Europe. Nucl. Fusion 47, 1524–1532 (2007).

    ADS  Google Scholar 

  52. 52

    Seki, Y. et al. in Proc. 25th IAEA Fusion Energy Conf. FIP/1-1. (IAEA, 2014).

  53. 53

    Hasegawa, A. et al. in Proc. 25th IAEA Fusion Energy Conf. MPT/1-4 (IAEA, 2014).

  54. 54

    Zohm, H. for the ASDEX Upgrade Team and the EUROfusion MST1 Team Recent ASDEX Upgrade research in support of ITER and DEMO. Nucl. Fusion 55, 104010 (2015).

    Google Scholar 

  55. 55

    Peacock, N. J. et al. Measurement of the electron temperature by Thomson scattering in tokamak T3. Nature 224, 488–490 (1969).

    ADS  Google Scholar 

  56. 56

    Rebut, P. H. et al. JET Project – Design Proposal EUR-JET-R5 (Commission of the European Communities, 1975).

  57. 57

    Strachan, J. et al. Fusion power production from TFTR plasmas fueled with deuterium and tritium. Phys. Rev. Lett 72, 3526–3529 (1994).

    ADS  Google Scholar 

  58. 58

    Hawryluk, R. J. et al. Confinement and heating of a deuterium–tritium plasma. Phys. Rev. Lett. 72, 3530–3533 (1994).

    ADS  Google Scholar 

  59. 59

    McGuire, K. M. et al. Review of deuteriumtritium results from the Tokamak Fusion Test Reactor. Phys. Plasmas 2, 2176–2188 (1995).

    ADS  Google Scholar 

  60. 60

    Ishida, S. et al. in Proc. 16th IAEA Conference on Fusion Energy Vol. 1, 315–330 (IAEA, 1997).

  61. 61

    Fujita, T. et al. High performance experiments in JT-60U reversed shear discharges. Nucl. Fusion 39, 1627–1636 (1999).

    ADS  Google Scholar 

  62. 62

    Keilhacker, M. et al. High fusion performance from deuterium-tritium plasmas in JET. Nucl. Fusion 39, 209–234 (1999).

    ADS  Google Scholar 

  63. 63

    Jacquinot, J. & the JET Team Deuterium-tritium operation in magnetic confinement experiments: results and underlying physics. Plasma Phys. Control. Fusion 41, A13–A46 (1999).

    Google Scholar 

  64. 64

    Tokitani, M. et al. Plasma wall interaction in long-pulse helium discharge in LHD Microscopic modification of the wall surface and its impact on particle balance and impurity generation. J. Nucl. Mater. 463, 91–98 (2015).

    ADS  Google Scholar 

  65. 65

    Helander, P. et al. Stellarator and tokamak plasmas: a comparison. Plasma Phys. Control. Fusion 54, 124009 (2012).

    ADS  Google Scholar 

  66. 66

    Grieger, G. et al. Physics optimization of stellarators. Phys. Fluids B 4, 2081–2091 (1992).

    ADS  Google Scholar 

  67. 67

    Bosch, H.-S. et al. Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X. Nucl. Fusion 53, 126001 (2013).

    ADS  Google Scholar 

  68. 68

    Melnikov, A. V. Applied and fundamental aspects of fusion science. Nature Phys. 12, 386–390 (2016).

    ADS  Google Scholar 

  69. 69

    Interview with Bernard Bigot: building the way to fusion energy. Nature Phys. 12, 395–397 (2016).

    ADS  Google Scholar 

  70. 70

    Progress in ITER Physics Basis. Nucl. Fusion 47, S1–S414 (2007); corrigendum 48, 099801 (2008).

  71. 71

    Vlad, G. et al. Alfvéic instabilities driven by fusion generated alpha particles in ITER scenarios. Nucl. Fusion 46, 1–16 (2006).

    ADS  Google Scholar 

  72. 72

    Giancarli, L. M. et al. Overview of the ITER TBM Program. Fusion Eng. Des. 87, 395–402 (2012).

    Google Scholar 

  73. 73

    Sborchia, C. et al. The ITER magnet systems: progress on construction. Nucl. Fusion 54, 013006 (2014).

    ADS  Google Scholar 

  74. 74

    Toigo, V. et al. in Proc. 25th IAEA Fusion Energy Conf. FIP/2-4Rc (IAEA, 2014).

  75. 75

    Wilson, J. R. & Bonoli, P. T. Progress on ion cyclotron range of frequencies heating physics and technology in support of the International Tokamak Experimental Reactor. Phys. Plasmas 22, 021801 (2015).

    ADS  Google Scholar 

  76. 76

    Omori, T. et al. Overview of the ITER EC H&CD system and its capabilities. Fusion Eng. Des. 86, 951–954 (2011).

    Google Scholar 

  77. 77

    Hoang, G. T. et al. A lower hybrid current drive system for ITER. Nucl. Fusion 49, 075001 (2009).

    ADS  Google Scholar 

  78. 78

    Motojima, O. The ITER project construction status. Nucl. Fusion 55, 104023 (2015).

    ADS  Google Scholar 

  79. 79

    Buckingham, R. & Loving, A. Remote-handling challenges in fusion research and beyond. Nature Phys. 12, 391–393 (2016).

    ADS  Google Scholar 

  80. 80

    Summary of the ITER Final Design Report Ch. 8 (IAEA, 2001).

  81. 81

    Pampin, R. et al. Activation analyses updating the ITER radioactive waste assessment. Fusion Eng. Des. 87, 1230–1234 (2012).

    Google Scholar 

  82. 82

    Hill, D. N. & the DIII-D team. DIII-D research towards resolving key issues for ITER and steady-state tokamaks. Nucl. Fusion 53, 104001 (2013).

    ADS  Google Scholar 

  83. 83

    Encheva, A. et al. in Proc. 25th IAEA Fusion Energy Conf. FIP/1-5 (IAEA, 2014).

  84. 84

    Buttery, R. J. & the DIII-D team. DIII-D research to address key challenges for ITER and fusion energy. Nucl. Fusion 55, 104017 (2015).

    ADS  Google Scholar 

  85. 85

    Baylor, L. R. et al. in Proc. 25th IAEA Fusion Energy Conf. FIP/2-1 (IAEA, 2014).

  86. 86

    Zohm, H. On the minimum size of DEMO. Fus. Sci. Technol. 58, 613–624 (2010).

    Google Scholar 

  87. 87

    Ishida, S., Barabaschi, P., Kamada, Y. & the JT-60SA Team Overview of the JT-60SA project. Nucl. Fusion 51, 094018 (2011).

    ADS  Google Scholar 

  88. 88

    Barabaschi, P. et al. in Proc. 25th IAEA Fusion Energy Conf. OV/3-2 (IAEA, 2014).

    Google Scholar 

  89. 89

    Angioni, C. et al. Density peaking, anomalous pinch, and collisionality in tokamak plasmas. Phys. Rev. Lett. 90, 205003 (2003).

    ADS  Google Scholar 

  90. 90

    Warmer, F. System code analysis of helias fusion reactor and economic comparison to tokamaks. IEEE Trans. Plasma Sci. (2016).

  91. 91

    Cowley, S. C. The quest for fusion power. Nature Phys. 12, 384–386 (2016).

    ADS  Google Scholar 

  92. 92

    Mineral Commodities Summaries (US Geological Survey, 2015);

  93. 93

    Evans, R. K. An Abundance of Lithium (North Carolina State University, 2008);

    Google Scholar 

  94. 94

    Evans, R. K. An Abundance of Lithium Part Two (EV World, 2008);

    Google Scholar 

  95. 95

    Nuttal, W. J., Clarke, R. H. & Glowacki, B. A. Stop squandering helium. Nature 485, 573–575 (2012).

    ADS  Google Scholar 

  96. 96

    Peterson, J. B. in The Future of Helium as a Natural Resource (eds Nuttall, W. J., Clarke, R. & Glowacki, B. A.) 48–54 (Routledge, 2012).

    Google Scholar 

  97. 97

    A Conceptual Study of Commercial Fusion Power Plants; (European Fusion Development Agreement, 2005);

  98. 98

    Safety and Environmental Impact of Fusion (European Fusion Development Agreement, 2001);

  99. 99

    Knaster, J. et al. IFMIF, the European-Japanese efforts under the Broader Approach Agreement towards a Li(d, xn) neutron source: current status and future options. Nucl. Mater. Energy (in the press).

  100. 100

    Gusev, V. K., Alladio, F. & Morris, A. W. The basics of spherical tokamaks and progress in European research. Plasma Phys. Control. Fusion 45, A59–A82 (2003).

    ADS  Google Scholar 

  101. 101

    Kirk, A. et al. Structure of ELMs in MAST and the implications for energy deposition. Plasma Phys. Control. Fusion 47, 315 (2005).

    ADS  Google Scholar 

Download references


J.O. and R.K. have the great pleasure to thank M. Van Schoor for pertinent valuable advice and discussions when writing this Review.

Author information



Corresponding author

Correspondence to J. Ongena.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ongena, J., Koch, R., Wolf, R. et al. Magnetic-confinement fusion. Nature Phys 12, 398–410 (2016).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing