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Fusion Wiki

An open, citation-bearing reference covering the physics, machines, fuels, materials, diagnostics, programs, and history of fusion energy. 396 entries and growing.

Confinement Schemes

Aneutronic fusionAneutronic fusion refers to any form of fusion power in which neutrons carry no more than 1% of the total released energy. These reactions primarily release energy as charged particles, offering potential advantages such as reduced material activation, simplified heat management, and the possibility of direct energy conversion.
Axisymmetric mirrorAn axisymmetric mirror is a magnetic confinement fusion device that uses a linear magnetic field with strengthened ends to confine plasma. Its axial symmetry simplifies engineering and allows for high plasma beta, but makes it susceptible to magnetohydrodynamic instabilities, which modern designs aim to overcome.
Beam-target fusionBeam-target fusion is a method of producing nuclear fusion reactions by directing a high-energy beam of ions onto a target containing fusion fuel. While inefficient for net energy production, it is a widely used technique for creating compact, high-flux neutron sources for research and industrial applications.
Colliding beam fusionColliding beam fusion (CBF) is a class of fusion energy concepts where fusion is produced by directing two or more accelerated beams of fuel ions at each other. This approach aims to create fusion reactions from high relative kinetic energy in a non-thermal plasma, contrasting with thermonuclear methods.
Compact fusion reactor conceptA compact fusion reactor is a conceptual or developmental fusion power plant design aiming for significantly smaller physical size, lower capital cost, and faster development timelines than conventional large-scale devices. These concepts often rely on high-temperature superconductors or alternative confinement schemes to achieve high power density.
Compact toroidA compact toroid (CT) is a self-contained toroidal plasma configuration in which the confining magnetic fields are generated primarily by internal plasma currents, rather than by external toroidal field coils. This allows for a simpler, more compact reactor design compared to devices like tokamaks.
Cusp confinementCusp confinement is a magnetic confinement fusion scheme that uses opposing magnetic fields to create a central null-point and surrounding high-field regions. This geometry offers inherent magnetohydrodynamic stability and high plasma beta, but faces challenges with particle losses through the cusp regions.
Dense plasma focusThe dense plasma focus (DPF) is a pulsed-power device that uses electromagnetic acceleration and compression to create a short-lived, hot, dense plasma pinch. It is studied as a compact fusion device and as a source of neutrons, ions, and X-rays for various industrial and scientific applications.
Direct-drive ICFDirect-drive inertial confinement fusion (ICF) is a method for achieving nuclear fusion where high-power laser beams directly irradiate a spherical fuel capsule. The laser energy ablates the capsule's surface, creating a rocket-like effect that symmetrically compresses and heats the fuel to ignition conditions.
Farnsworth–Hirsch fusorThe Farnsworth–Hirsch fusor is a device for achieving nuclear fusion based on the principle of Inertial Electrostatic Confinement (IEC). It uses an electrostatic field to accelerate ions toward a central point, creating a dense, hot plasma core where fusion reactions can occur.
Fast ignition ICFFast ignition is an inertial confinement fusion (ICF) concept that separates the compression and ignition stages. A fuel capsule is first compressed to high density by a driver, then ignited by a separate, ultra-intense, short-pulse laser or particle beam, potentially lowering driver energy requirements.
Field-reversed configuration (FRC)A Field-Reversed Configuration (FRC) is a compact toroid plasma confined by purely poloidal magnetic fields, sustained by internal plasma currents. Its high-beta nature and simple, linear geometry make it an alternative magnetic confinement concept for fusion energy.
Gas dynamic trapThe Gas Dynamic Trap (GDT) is a linear magnetic mirror confinement system characterized by a high mirror ratio and a plasma length much greater than the ion mean free path. This allows the plasma to be treated as a fluid, with losses governed by gas-dynamic equations, making it a candidate for a volumetric fusion neutron source.
Heavy-ion inertial fusionHeavy-ion inertial fusion (HIF) is an inertial confinement fusion approach that uses high-energy beams of heavy ions to compress and heat a fuel target to fusion conditions. It is pursued as a potential pathway to commercial fusion energy due to the high efficiency and repetition rate of heavy-ion accelerators.
HeliacA Heliac (Helical Axis Stellarator) is a magnetic confinement fusion device characterized by a magnetic axis that follows a helical path around a central conductor. This configuration generates a strong rotational transform, enabling stable, high-beta plasma confinement without a net toroidal plasma current.
HeliotronThe heliotron is a magnetic confinement fusion concept, a subclass of the stellarator, characterized by a continuous helical coil winding and a set of poloidal field coils. This configuration generates the entire confining magnetic field externally, enabling inherently steady-state, disruption-free plasma operation.
Indirect-drive ICF (hohlraum)Indirect-drive inertial confinement fusion (ICF) is a method for achieving nuclear fusion by using a high-Z cavity, called a hohlraum, to convert driver energy (typically from lasers) into a uniform bath of soft X-rays. These X-rays then symmetrically compress and heat a fuel capsule to ignition conditions.
Inertial confinement fusion (ICF)Inertial confinement fusion (ICF) is a process that initiates nuclear fusion by rapidly compressing and heating a small target containing fusion fuel. The target's own inertia confines the fuel at extreme temperatures and densities long enough for a significant number of fusion reactions to occur.
Inertial electrostatic confinement (IEC)Inertial electrostatic confinement (IEC) is a non-magnetic fusion energy concept that uses electrostatic fields to accelerate and confine ions in a potential well. Ions are accelerated towards a central point, where high density and temperature can lead to fusion reactions.
Levitated dipole experimentThe levitated dipole is a magnetic confinement fusion concept that uses a superconducting coil, magnetically levitated within a vacuum chamber, to create a dipole magnetic field similar to a planetary magnetosphere. This configuration is designed to confine high-beta plasma in a steady state with favorable stability properties.
Magnetic mirrorA magnetic mirror is a plasma confinement device that uses a non-uniform magnetic field to reflect charged particles. The field is stronger at two ends and weaker in the middle, creating a magnetic 'bottle' to trap hot plasma along open field lines, representing a linear alternative to toroidal systems.
Magnetized liner inertial fusion (MagLIF)Magnetized Liner Inertial Fusion (MagLIF) is a magneto-inertial fusion (MIF) concept that uses a pulsed-power driver to rapidly implode a cylindrical metal liner. The liner contains pre-magnetized and pre-heated fusion fuel, combining magnetic insulation with inertial confinement to achieve fusion conditions.
Magnetized target fusion (MTF)Magnetized Target Fusion (MTF) is a hybrid approach to fusion energy that combines features of magnetic and inertial confinement. It involves creating a moderately dense, magnetized plasma target which is then rapidly compressed, or imploded, to achieve fusion conditions at intermediate density and confinement times.
Magneto-inertial fusion (MIF)Magneto-inertial fusion (MIF) is a class of fusion energy approaches that uses a magnetic field to insulate a plasma and reduce thermal conduction losses, while simultaneously using inertial compression to heat the plasma to fusion conditions. This hybrid method operates in a density-timescale regime intermediate between traditional magnetic and inertial confinement fusion.
Muon-catalyzed fusionMuon-catalyzed fusion (μCF) is a process where a negatively charged muon replaces an electron in a hydrogen isotope molecule, drastically reducing the internuclear distance and enabling nuclear fusion to occur at temperatures far below those required for thermonuclear approaches.
Optimized stellaratorAn optimized stellarator is a magnetic confinement fusion device that uses complex, non-axisymmetric 3D magnetic coils to create a stable plasma equilibrium with reduced neoclassical transport and improved magnetohydrodynamic stability, addressing key limitations of classical stellarator designs.
Picosecond-pulse laser fusionPicosecond-pulse laser fusion is an inertial confinement fusion (ICF) approach that uses ultra-intense, short-duration laser pulses (1-100 ps) to ignite a pre-compressed deuterium-tritium fuel target. It aims to achieve ignition with lower driver energy by separating the compression and ignition phases.
Plasma jet–driven MIFPlasma jet–driven magneto-inertial fusion (PJMIF) is a fusion energy approach that uses an array of merging, high-velocity plasma jets to form a liner that compresses a magnetized plasma target to fusion conditions. It is a sub-class of magneto-inertial fusion (MIF) that aims to achieve net energy gain in a pulsed, repetitively-driven system.
PolywellThe Polywell is an experimental inertial electrostatic confinement (IEC) fusion concept that uses a quasi-spherical magnetic cusp field to trap electrons. This electron cloud forms a virtual cathode, which electrostatically confines and accelerates ions to fusion conditions, aiming to overcome the grid losses of traditional fusors.
Projectile fusionProjectile fusion is a form of inertial confinement fusion where a hypervelocity projectile impacts a target containing fusion fuel. The projectile's kinetic energy is converted into immense pressure and temperature upon impact, creating the conditions necessary for nuclear fusion reactions.
Pulsed magnetic fusionPulsed magnetic fusion encompasses a class of magnetic confinement approaches that heat and compress a plasma on short timescales (microseconds to milliseconds) using pulsed magnetic fields. These systems aim for high plasma density and pressure to achieve fusion conditions without requiring steady-state operation.
Pyroelectric fusionPyroelectric fusion is a method of producing nuclear fusion reactions by using the intense electric fields generated by a pyroelectric crystal during thermal cycling. These fields accelerate ions into a target, creating a compact, non-radioactive neutron source, but it is not considered a viable path to net energy gain.
Quasi-axisymmetric stellaratorA quasi-axisymmetric stellarator is a magnetic confinement fusion device designed to have a magnetic field strength that approximates the continuous toroidal symmetry of a tokamak. This design combines the intrinsic stability and steady-state potential of a stellarator with the superior particle confinement of a tokamak.
Quasi-helically symmetric stellaratorA quasi-helically symmetric stellarator is a magnetic confinement fusion device with a 3D magnetic field optimized to possess a hidden helical symmetry. This quasi-symmetry dramatically reduces neoclassical transport, a key energy loss mechanism, enabling confinement properties comparable to a tokamak.
Reversed field pinch (RFP)The reversed-field pinch (RFP) is a magnetic confinement fusion concept where the toroidal magnetic field spontaneously reverses direction in the outer region of the plasma. This configuration allows for confinement with a relatively weak external toroidal field, potentially leading to a more compact reactor design.
Sheared-flow-stabilized Z-pinchA sheared-flow-stabilized Z-pinch is a magnetic confinement fusion concept that uses axial plasma flow with a radial velocity gradient (shear) to suppress magnetohydrodynamic instabilities, particularly the 'sausage' and 'kink' modes, that plague traditional Z-pinches, enabling longer confinement times.
Shock ignitionShock ignition is an advanced inertial confinement fusion scheme that separates the fuel compression and ignition phases. A long, low-intensity laser pulse compresses the fuel, followed by a short, high-intensity spike that launches a strong shock wave to ignite the pre-compressed core.
Spherical tokamakA spherical tokamak (ST) is a type of tokamak with a very low aspect ratio, appearing almost spherical. This geometry offers potential advantages for plasma stability and efficiency, enabling higher plasma pressure for a given magnetic field strength, but presents significant engineering challenges.
SpheromakThe spheromak is a magnetic confinement fusion concept where the confining magnetic fields are generated almost entirely by internal plasma currents. This self-organizing plasma configuration, a type of compact toroid, eliminates the need for a central toroidal field coil, offering a simpler and more compact reactor design.
StellaratorThe stellarator is a toroidal magnetic confinement fusion device that uses external, non-planar coils to generate a twisted, three-dimensional magnetic field to confine plasma. Unlike tokamaks, stellarators do not require a large net plasma current, making them inherently stable against disruptions and suitable for steady-state operation.
Tandem mirrorThe tandem mirror is a linear magnetic confinement fusion concept that uses electrostatic potentials to plug the ends of a central solenoid, significantly reducing axial plasma losses that plague simple magnetic mirrors. It combines a long, simple central cell with complex end cells to improve ion confinement.
TokamakThe tokamak is a magnetic confinement device that uses a toroidal magnetic field and a plasma-induced poloidal field to contain a high-temperature plasma. It is the most developed and widely researched concept for achieving controlled thermonuclear fusion.
Z-pinchThe Z-pinch is a plasma confinement scheme where an axial electric current (in the 'z' direction) generates an azimuthal magnetic field that compresses and confines the plasma. It is one of the earliest concepts for controlled fusion, now primarily used in pulsed-power applications and explored in novel fusion reactor designs.
Z-pinch / ICF hybridA Z-pinch/ICF hybrid is a magneto-inertial fusion (MIF) approach that uses the powerful magnetic field from a Z-pinch to rapidly compress a pre-magnetized and pre-heated fuel target. This method combines principles of both magnetic and inertial confinement to achieve fusion conditions.
θ-pinchThe theta-pinch (θ-pinch) is a magnetic confinement concept where a plasma is compressed and heated by a rapidly pulsed axial magnetic field. This field induces a strong azimuthal (theta-direction) current, creating an inward Lorentz force that confines the plasma in a cylindrical geometry.

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