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    Magnetic vs inertial fusion: the main ways to confine a plasma

    Fusion machines fall into two families. Magnetic confinement holds a hot plasma in magnetic fields; inertial confinement heats and compresses a fuel capsule fast enough to reach fusion conditions.[1][2] Hybrids such as magnetized target fusion and pulsed field-reversed configurations sit in between and are mostly pursued by private companies.[3][4]

    Editor reviewedUpdated Fusion energyPhysicsEnergy and climate

    Two ways to hold a star

    Fusion fuel must be extremely hot, dense enough, and held together long enough to fuse.[5] There are two basic strategies. Magnetic confinement uses strong magnetic fields as an invisible bottle that holds the hot plasma away from the walls.[1] Inertial confinement takes a tiny fuel pellet and crushes and heats it so quickly that it reaches fusion conditions.[2]

    Both families chase the same triple product of density, temperature and confinement time, but they trade the terms differently: magnetic machines hold a plasma for long periods, and inertial machines rely on rapid compression of a capsule.[6][1][2] Magnetic machines are judged by plasma Q, the ratio of fusion power to heating power. Inertial machines are judged by target gain, the ratio of fusion yield to driver energy on target.[7][8]

    Magnetic confinement: tokamaks and stellarators

    The tokamak was developed in the Soviet Union in the late 1960s and has become the most widely adopted magnetic design.[9] It confines plasma in a doughnut-shaped vessel. Part of its magnetic field comes from a large current driven through the plasma itself.[10][11] A tokamak holds the fusion-energy record: the UK’s JET released 69 megajoules in its final deuterium-tritium campaign.[12] iter and Commonwealth Fusion Systems’ SPARC are both tokamaks.[13][14]

    The stellarator makes its whole confining field with external, twisted coils, so it needs no plasma current. This allows steady operation and makes the plasma less prone to instabilities.[15] The price is very complex coils: wendelstein-7-x uses 50 non-planar superconducting coils.[16]

    Inertial confinement: lasers and capsules

    At the national-ignition-facility, 192 laser beams converge on a target the size of a peppercorn.[17] In the “indirect drive” scheme, the beams heat the inside of a centimetre-sized cylinder called a hohlraum. The hohlraum fills with X-rays that make a deuterium-tritium capsule implode, much like a rocket.[17] This produced ignition in December 2022 and a record target gain of 4.13 in April 2025.[18][8] A power plant would need far more efficient lasers firing many times a second. Physics World reported in 2023 that diode-pumped lasers could reach 20 percent efficiency, and one company aimed for 18 percent at 10 to 20 shots per second.[19]

    In between: pulsed and magnetized-target concepts

    Several private companies combine features of both families:

    • Field-reversed configurations (FRCs). helion-energy magnetically compresses pulsed, high-beta FRC plasmas. It aims to recover the energy directly as electricity instead of running a steam turbine.[4]
    • Magnetized target fusion (MTF). General Fusion compresses a magnetized plasma with a metal wall over milliseconds. In October 2026 it reported electron temperatures above 1 keV (12 million degrees Celsius) on its LM26 machine, a result not yet independently verified.[3]

    These concepts are less mature than tokamaks. Their published results come mostly from the companies themselves, and their next milestones are company-set targets.[20][21]

    How they compare in 2026

    ApproachLeading exampleBest sourced result
    TokamakJET, ITER, SPARC69 MJ fusion energy (JET); 1,337 s pulse (WEST)
    StellaratorWendelstein 7-XRecord triple product held for 43 s (2025)
    Laser (indirect drive)NIFTarget gain 4.13, 8.6 MJ yield (2025)
    Pulsed FRCHelion PolarisMeasurable D-T fusion, 150 million °C (company report, not yet independently verified)
    Magnetized targetGeneral Fusion LM26Above 1 keV electron temperature (company report, not yet independently verified)

    Sources for the table: JET and WEST,[12][22] Wendelstein 7-X,[23] NIF,[8] Helion[21] and General Fusion.[3]

    Questions readers ask

    What is the difference between a tokamak and a stellarator?

    Both are doughnut-shaped magnetic machines. A tokamak drives an electric current through the plasma to help create its magnetic field, while a stellarator uses twisted external coils instead, so it can run continuously.[11][15]

    How does laser fusion work?

    At the National Ignition Facility, up to 192 laser beams heat a small hollow cylinder called a hohlraum, which bathes a fuel capsule in X-rays and makes it implode.[17]

    What is magnetized target fusion?

    It compresses a magnetized plasma mechanically. General Fusion's LM26 machine uses a metal wall that squeezes the plasma over milliseconds rather than lasers.[3]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      Magnetic confinement fusion holds the plasma with carefully designed magnetic fields long enough for fusion reactions to occur. confirmedas of 2026-10-10

    2. [2]

      Inertial confinement fusion heats and compresses a fuel capsule rapidly enough to reach the temperatures and densities needed for fusion. confirmedas of 2026-10-10

    3. [3]

      On 8 October 2026 General Fusion said its LM26 magnetized target fusion machine had reached electron temperatures above 12 million degrees Celsius (more than 1 keV) by compressing plasma with a metal wall over milliseconds. reportedas of 2026-10-08

    4. [4]

      Helion's machines magnetically compress pulsed, high-beta field-reversed configuration (FRC) plasmas and aim to recover energy directly as electricity rather than via heat and a steam turbine. confirmedas of 2026-10-10

    5. [5]

      In 1955 the British physicist John D. Lawson estimated the parameters needed for fusion to give more energy out than is put in, setting a minimum for the product of plasma density, confinement time and temperature. confirmedas of 2026-10-10

    6. [6]

      The triple product is the product of plasma density, energy confinement time and temperature, and is the standard figure of merit for fusion performance. confirmedas of 2026-10-10

    7. [7]

      ITER's main performance goal, Q of at least 10, means 500 megawatts of thermal fusion power from 50 megawatts of heating power put into the plasma, in 400-second pulses. confirmedas of 2026-10-10

    8. [8]

      On 7 April 2025 NIF set records for yield and target gain, producing 8.6 megajoules (plus or minus 0.45) from 2.08 megajoules of laser energy, a target gain of 4.13. confirmedas of 2026-10-10

    9. [9]

      The tokamak was first developed by Soviet researchers in the late 1960s and has been adopted worldwide as the most promising magnetic fusion configuration; its name is a Russian acronym for "toroidal chamber with magnetic coils". confirmedas of 2026-10-10

    10. [10]

      A tokamak is an experimental machine in which a fusion plasma is created and confined by strong magnetic fields in a doughnut-shaped (toroidal) vessel. confirmedas of 2026-10-10

    11. [11]

      In a tokamak, part of the confining (poloidal) magnetic field comes from a current driven inside the plasma by transformer action, whereas a stellarator generates it with external helical coils. confirmedas of 2026-10-10

    12. [12]

      In its final deuterium-tritium experiments, announced on 8 February 2024, the Joint European Torus (JET) in the UK produced a record 69 megajoules of fusion energy over 5 seconds from 0.2 milligrams of fuel. confirmedas of 2026-10-10

    13. [13]

      The ITER tokamak's volume and weight are nearly 10 times those of the largest existing tokamaks, and its combined toroidal field coils form a magnet with a cold mass over 6,000 tonnes storing 41 gigajoules. confirmedas of 2026-10-10

    14. [14]

      Commonwealth Fusion Systems says its SPARC tokamak in Devens, Massachusetts, is intended to be the first commercially relevant machine to demonstrate net fusion energy (Q>1). confirmedas of 2026-08-05

    15. [15]

      Because a stellarator has no plasma current, it can in principle run continuously (steady state) and is less prone to plasma instabilities than a tokamak. confirmedas of 2026-10-10

    16. [16]

      Wendelstein 7-X in Greifswald, Germany, confines its plasma with a system of 50 non-planar superconducting magnet coils and is designed for plasma discharges of up to 30 minutes. confirmedas of 2026-10-10

      • Wendelstein 7-X · Max Planck Institute for Plasma Physics (retrieved 2026-10-10)
    17. [17]

      In NIF's indirect-drive experiments, up to 192 laser beams are fired into a centimetre-sized hollow cylinder called a hohlraum, which turns the light into X-rays that implode a fuel capsule. confirmedas of 2026-10-10

      • Achieving fusion ignition · Lawrence Livermore National Laboratory (retrieved 2026-10-10)
      • How NIF works · Lawrence Livermore National Laboratory (retrieved 2026-10-10)
      • How NIF works · Lawrence Livermore National Laboratory (retrieved 2026-10-10)
      • How NIF works · Lawrence Livermore National Laboratory (retrieved 2026-10-10)
    18. [18]

      On 5 December 2022 the National Ignition Facility produced 3.15 megajoules of fusion energy from 2.05 megajoules of laser energy, the first laboratory fusion ignition. confirmedas of 2026-10-10

    19. [19]

      Diode-pumped lasers could reach efficiencies as high as 20 percent, and one laser-fusion company (Longview Fusion) aimed for 18 percent laser efficiency at 10 to 20 shots per second. confirmedas of 2023-01-20

    20. [20]

      General Fusion's next targets are compressional heating to 10 keV and then the Lawson criterion, and it plans to begin operating a first-of-a-kind plant around 2035. reportedas of 2026-10-08· forecast

    21. [21]

      On 13 February 2026 Helion said its Polaris prototype was the first privately developed fusion machine to demonstrate measurable deuterium-tritium fusion and had reached plasma temperatures of 150 million degrees Celsius; Helion also said it was the first company approved to possess and use tritium to demonstrate fusion energy production. reportedas of 2026-02-13

    22. [22]

      On 12 February 2025 France's WEST tokamak set a plasma-duration record of 1,337 seconds (about 22 minutes). confirmedas of 2026-10-10

    23. [23]

      On 22 May 2025 Wendelstein 7-X sustained a record triple product for long plasma discharges for 43 seconds, surpassing tokamak results for comparable durations. confirmedas of 2026-10-10

    Revision history (2)
    1. Page created.
    2. Refresh: verbatim re-quoting of the NIF wall-plug efficiency and diode-pumped laser excerpts, and of the Wendelstein 7-X triple-product record.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Magnetic vs inertial fusion: the main ways to confine a plasma." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/magnetic-vs-inertial-confinement

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