A reversed-field pinch (RFP) is a device used to produce and contain near-thermonuclear plasmas. It is a toroidal pinch which uses a unique magnetic field configuration as a scheme to magnetically confine a plasma, primarily to study magnetic confinement fusion. Its magnetic geometry is somewhat different from that of the more common tokamak. As one moves out radially, the portion of the magnetic field pointing toroidally reverses its direction, giving rise to the term reversed field. This configuration can be sustained with comparatively lower fields than that of a tokamak of similar power density. One of the disadvantages of this configuration is that it tends to be more susceptible to non-linear effects and turbulence. This makes it a useful system for studying non-ideal (resistive) magnetohydrodynamics. RFPs are also used in studying astrophysical plasmas, which share many common features.
The largest Reversed Field Pinch device presently in operation is the RFX (R/a = 2/0.46) in Padua, Italy. Others include the MST (R/a = 1.5/0.5) in the United States, EXTRAP T2R (R/a = 1.24/0.18) in Sweden, RELAX (R/a = 0.51/0.25) in Japan, and KTX (R/a = 1.4/0.4) in China.
Unlike the Tokamak, which has a much larger magnetic field in the toroidal direction than the poloidal direction, an RFP has a comparable field strength in both directions (though the sign of the toroidal field reverses). Moreover, a typical RFP has a field strength approximately one half to one tenth that of a comparable Tokamak. The RFP also relies on driving current in the plasma to reinforce the field from the magnets through the dynamo effect.
The reversed-field pinch works towards a state of minimum energy.
The magnetic field lines coil loosely around a center torus. They coil outwards. Near the plasma edge, the toroidal magnetic field reverses and the field lines coil in the reverse direction.
Internal fields are bigger than the fields at the magnets.
The RFP has many features that make it a promising configuration for a potential fusion reactor.
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La fusion par confinement magnétique (FCM) est une méthode de confinement utilisée pour porter une quantité de combustible aux conditions de température et de pression désirées pour la fusion nucléaire. De puissants champs électromagnétiques sont employés pour atteindre ces conditions. Le combustible doit au préalable être converti en plasma, celui-ci se laisse ensuite influencer par les champs magnétiques. Il s'agit de la méthode utilisée dans les tokamaks toriques et sphériques, les stellarators et les machines à piège à miroirs magnétiques.
A pinch (or: Bennett pinch (after Willard Harrison Bennett), electromagnetic pinch, magnetic pinch, pinch effect, or plasma pinch.) is the compression of an electrically conducting filament by magnetic forces, or a device that does such. The conductor is usually a plasma, but could also be a solid or liquid metal. Pinches were the first type of device used for experiments in controlled nuclear fusion power. Pinches occur naturally in electrical discharges such as lightning bolts, planetary auroras, current sheets, and solar flares.
thumb|upright|Le soleil est une boule de plasma. thumb|Lampe à plasma.|168x168px thumb|upright|Les flammes de haute température sont des plasmas. L'état plasma est un état de la matière, tout comme l'état solide, l'état liquide ou l'état gazeux, bien qu'il n'y ait pas de transition brusque pour passer d'un de ces états au plasma ou réciproquement. Il est visible sur Terre, à l'état naturel, le plus souvent à des températures élevées favorables aux ionisations, signifiant l’arrachement d'électrons aux atomes.
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Couvre les configurations d'équilibre MHD, y compris les concepts de tokamak et de stellarator, les équations d'équilibre de force et les facteurs de sécurité.
Learn the basics of plasma, one of the fundamental states of matter, and the different types of models used to describe it, including fluid and kinetic.
Learn the basics of plasma, one of the fundamental states of matter, and the different types of models used to describe it, including fluid and kinetic.
The superconducting magnet system of the Divertor Tokamak Test (DTT) facility, composed of 18 toroidal field (TF) coils, 6 poloidal field coils and a central solenoid, has been designed and many procurements have been launched. Some manufacturing aspects a ...
Iop Publishing Ltd2024
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Simulations of plasma turbulence in a linear plasma device configuration are presented. These simulations are based on a simplified version of the gyrokinetic (GK) model proposed by Frei et al. [J. Plasma Phys. 86, 905860205 (2020)], where the full-F distr ...
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