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Resonant Magnetic Perturbations
Resonant magnetic perturbations (RMPs) are a special type of magnetic field perturbations used to control burning plasma instabilities called edge-localized modes (ELMs) in magnetic fusion devices such as tokamaks. The efficiency of RMPs for controlling ELMs was first demonstrated on the tokamak DIII-D in 2003. Normally the rippled magnetic field will only suppress ELMs for very narrow ranges of the plasma current. See also *Plasma instability The stability of a plasma is an important consideration in the study of plasma physics. When a system containing a plasma is at equilibrium, it is possible for certain parts of the plasma to be disturbed by small perturbative forces acting on it ... * COMPASS tokamak * NSTX-U, also uses RMPs to control ELMs References Further reading ''Effect of resonant magnetic perturbations on ELMs in connected double null plasmas in MAST''''RMP ELM suppression in DIII-D plasmas with ITER similar shapes and collisionalities'' 2008 RMP for ITER-li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burning Plasma
Plasma, one of the four fundamental states of matter, consists of a gas of ions and free electrons. A burning plasma is one in which most of the plasma heating comes from fusion reactions involving thermal plasma ions. The Sun In the Sun and other similar stars, those fusion reactions involve hydrogen ions. The high temperatures needed to sustain fusion reactions are maintained by a self-heating process in which energy from the fusion reaction heats the thermal plasma ions via particle collisions. A plasma enters what scientists call the burning plasma regime when the self-heating power exceeds any external heating. The Sun is a burning plasma that has reached "ignition", meaning the Sun's plasma temperature is maintained solely by energy released from fusion. The Sun has been burning hydrogen for 4.5 billion years and is about halfway through its life cycle. The National Ignition Facility It was announced in 2022 that a burning plasma had been achieved at the National Ignitio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edge-localized Mode
An edge-localized mode (ELM) is a disruptive instability occurring in the edge region of a tokamak plasma due to the quasi-periodic relaxation of a transport barrier previously formed during a transition from low to high-confinement mode. This phenomenon was first observed in the ASDEX tokamak in 1981. Diamagnetic effects in the model equations expand the size of the parameter space in which solutions of repeated sawteeth can be recovered compared to a resistive MHD model. An ELM can expel up to 20 percent of the reactor's energy. Issues ELM is a major challenge in magnetic fusion research with tokamaks, as these instabilities can: * damage wall components (in particular divertor plates) by ablating them away due to their extremely high energy transfer rate (GW/m2); * potentially couple or trigger other instabilities, such as the resistive wall mode (RWM) or the neoclassical tearing mode (NTM). Prevention and control A variety of experiments/simulations have attempted to m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tokamak
A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. , it was the leading candidate for a practical fusion reactor. Tokamaks were initially conceptualized in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov, inspired by a letter by Oleg Lavrentiev. The first working tokamak was attributed to the work of Natan Yavlinsky on the T-1 in 1958. It had been demonstrated that a stable plasma equilibrium requires magnetic field lines that wind around the torus in a helix. Devices like the z-pinch and stellarator had attempted this, but demonstrated serious instabilities. It was the development of the concept now known as the safety factor (labelled ''q'' in mathematical notation) that guided tokamak development; by arranging the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DIII-D
DIII-D is a tokamak that has been operated since the late 1980s by General Atomics (GA) in San Diego, USA, for the U.S. Department of Energy. The DIII-D National Fusion Facility is part of the ongoing effort to achieve magnetically confined fusion. The mission of the DIII-D Research Program is to establish the scientific basis for the optimization of the tokamak approach to fusion energy production. DIII-D was built on the basis of the earlier Doublet III, the third in a series of machines built at GA to experiment with tokamaks having non-circular plasma cross sections. This work demonstrated that certain shapes strongly suppressed a variety of instabilities in the plasma, which led to much higher plasma pressure and performance. DIII-D is so-named because the plasma is shaped like the letter D, a shaping that is now widely used on modern designs, and has led to the class of machines known as "advanced tokamaks." Advanced tokamaks are characterized by operation at high plasma β ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Review Letters
''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. As also confirmed by various measurement standards, which include the ''Journal Citation Reports'' impact factor and the journal ''h''-index proposed by Google Scholar, many physicists and other scientists consider ''Physical Review Letters'' to be one of the most prestigious journals in the field of physics. ''According to Google Scholar, PRL is the journal with the 9th journal h-index among all scientific journals'' ''PRL'' is published as a print journal, and is in electronic format, online and CD-ROM. Its focus is rapid dissemination of significant, or notable, results of fundamental research on all topics related to all fields of physics. This is accomplished by rapid publication of short reports, called "Letters". Papers are published and available electronically one article at a time. When published in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Instability
The stability of a plasma is an important consideration in the study of plasma physics. When a system containing a plasma is at equilibrium, it is possible for certain parts of the plasma to be disturbed by small perturbative forces acting on it. The stability of the system determines if the perturbations will grow, oscillate, or be damped out. In many cases, a plasma can be treated as a fluid and its stability analyzed with magnetohydrodynamics (MHD). MHD theory is the simplest representation of a plasma, so MHD stability is a necessity for stable devices to be used for nuclear fusion, specifically magnetic fusion energy. There are, however, other types of instabilities, such as velocity-space instabilities in magnetic mirrors and systems with beams. There are also rare cases of systems, e.g. the field-reversed configuration, predicted by MHD to be unstable, but which are observed to be stable, probably due to kinetic effects. Plasma instabilities Plasma instabilities can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COMPASS Tokamak
COMPASS, short for Compact Assembly, is a compact tokamak fusion energy device originally completed at the Culham Science Centre in 1989, upgraded in 1992, and operated until 2002. It was designed as a flexible research facility dedicated mostly to plasma physics studies in circular and D-shaped plasmas. When it was decommissioned at Culham, it was offered to the European Commission and found a new home at the Institute of Plasma Physics of the Czech Academy of Sciences in Prague where it began operations once again in 2006. It officially ended its experimental runs on 20 August 2021 and will be disassembled to leave room for a new device, COMPASS-U. History The first plasma in COMPASS was produced in 1989 in a C-shaped vacuum vessel, i.e., in a simpler vessel with a circular cross-section. Pioneering experiments followed, including for example the ITER-relevant tests of magnetic field correction with saddle coils for Resonant magnetic perturbations (RMP) experiments or exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NSTX-U
The National Spherical Torus Experiment (NSTX) is a magnetic fusion device based on the ''spherical tokamak'' concept. It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. It entered service in 1999. In 2012 it was shut down as part of an upgrade program and became NSTX-U, for Upgrade. The spherical tokamak (ST) is an offshoot of the conventional tokamak design. Proponents claim that it has a number of practical advantages over these devices, some of them dramatic. For this reason the ST has seen considerable interest since it was proposed in the late 1980s. However, development remains effectively one generation behind mainline efforts such as JET. Other major experiments in the field include the pioneering START and MAST at Culham in the UK. NSTX studies the physics principles of spherically shaped plasmas—hot ionized gases in which nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Physics
Plasma ()πλάσμα , Henry George Liddell, Robert Scott, ''A Greek English Lexicon'', on Perseus is one of the . It contains a significant portion of charged particles – s and/or s. The presence of these charged particles is what primarily sets plasma apart from the other fundamental states of matter. It is the most abundant form of |
