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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] |
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] |
Joint European Torus
The Joint European Torus, or JET, is an operational magnetically confined plasma physics experiment, located at Culham Centre for Fusion Energy in Oxfordshire, UK. Based on a tokamak design, the fusion research facility is a joint European project with a main purpose of opening the way to future nuclear fusion grid energy. At the time of its design JET was larger than any comparable machine. JET was built with the hope of reaching ''scientific breakeven'' where the fusion energy gain factor ''Q'' =1.0. It began operation in 1983 and spent most of the next decade increasing its performance in a lengthy series of experiments and upgrades. In 1991 the first experiments including tritium were made, making JET the first reactor in the world to run on the production fuel of a 50–50 mix of tritium and deuterium. It was also decided to add a divertor design to JET, which occurred between 1991 and 1993. Performance was significantly improved, and in 1997 JET set the record for the cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomson Scattering
Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is the low-energy limit of Compton scattering: the particle's kinetic energy and photon frequency do not change as a result of the scattering. This limit is valid as long as the photon energy is much smaller than the mass energy of the particle: \nu\ll mc^2/h , or equivalently, if the wavelength of the light is much greater than the Compton wavelength of the particle (e.g., for electrons, longer wavelengths than hard x-rays). Description of the phenomenon In the low-energy limit, the electric field of the incident wave (photon) accelerates the charged particle, causing it, in turn, to emit radiation at the same frequency as the incident wave, and thus the wave is scattered. Thomson scattering is an important phenomenon in plasma physics and was first explained by the physicist J. J. Thomson. As long as the motion of the particle is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langmuir Probe
A Langmuir probe is a device used to determine the electron temperature, electron density, and electric potential of a plasma. It works by inserting one or more electrodes into a plasma, with a constant or time-varying electric potential between the various electrodes or between them and the surrounding vessel. The measured currents and potentials in this system allow the determination of the physical properties of the plasma. ''I-V'' characteristic of the Debye sheath The beginning of Langmuir probe theory is the ''I–V'' characteristic of the Debye sheath, that is, the current density flowing to a surface in a plasma as a function of the voltage drop across the sheath. The analysis presented here indicates how the electron temperature, electron density, and plasma potential can be derived from the ''I–V'' characteristic. In some situations a more detailed analysis can yield information on the ion density (n_i), the ion temperature T_i, or the electron energy distribution f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball-pen Probe
A ball-pen probe is a modified Langmuir probe used to measure the plasma potential in magnetized plasmas. The ball-pen probe balances the electron and ion saturation currents, so that its floating potential is equal to the plasma potential. Because electrons have a much smaller gyroradius than ions, a moving ceramic shield can be used to screen off an adjustable part of the electron current from the probe collector. Ball-pen probes are used in plasma physics, notably in tokamaks such as CASTOR, (Czech Academy of Sciences Torus) ASDEX Upgrade, COMPASS, ISTTOK, MAST, TJ-K, RFX, H-1 Heliac, IR-T1, GOLEM as well as low temperature devices as DC cylindrical magnetron in Prague and linear magnetized plasma devices in Nancy and Ljubljana. Principle If a Langmuir probe (electrode) is inserted into a plasma, its potential is not equal to the plasma potential \Phi because a Debye sheath forms, but instead to a floating potential V_ . The difference with the plasma potential is g ... [...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] |
List Of Fusion Experiments
Experiments directed toward developing fusion power are invariably done with dedicated machines which can be classified according to the principles they use to confine the plasma fuel and keep it hot. The major division is between magnetic confinement and inertial confinement. In magnetic confinement, the tendency of the hot plasma to expand is counteracted by the Lorentz force between currents in the plasma and magnetic fields produced by external coils. The particle densities tend to be in the range of to and the linear dimensions in the range of . The particle and energy confinement times may range from under a millisecond to over a second, but the configuration itself is often maintained through input of particles, energy, and current for times that are hundreds or thousands of times longer. Some concepts are capable of maintaining a plasma indefinitely. In contrast, with inertial confinement, there is nothing to counteract the expansion of the plasma. The confinement t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutral Beam Injection
Neutral-beam injection (NBI) is one method used to heat plasma inside a fusion device consisting in a beam of high-energy neutral particles that can enter the magnetic confinement field. When these neutral particles are ionized by collision with the plasma particles, they are kept in the plasma by the confining magnetic field and can transfer most of their energy by further collisions with the plasma. By tangential injection in the torus, neutral beams also provide momentum to the plasma and current drive, one essential feature for long pulses of burning plasmas. Neutral-beam injection is a flexible and reliable technique, which has been the main heating system on a large variety of fusion devices. To date, all NBI systems were based on positive precursor ion beams. In the 1990s there has been impressive progress in negative ion sources and accelerators with the construction of multi-megawatt negative-ion-based NBI systems at LHD (H0, 180 keV) and JT-60U (D0, 500 keV). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BPP LP Divertor COMPASS
BPP may refer to: Education * BPP Holdings, a holding company based in the United Kingdom * BPP Law School, a law school based in the United Kingdom and a constituent school of BPP University * BPP University, a private university based in the United Kingdom Mathematics * Bounded-error probabilistic polynomial time, a class of decision problems in computational complexity theory * Bin packing problem a problem in computational complexity theory Medicine * Biophysical profile, a prenatal ultrasound evaluation of fetal well-being * BPP (also Brom PP), a medicine used for treatment of upper respiratory tract infection et al., in tablet or other form, with Brompheniramine, Phenylephrine and Phenylpropanolamine as active ingredients. Places * Bang Pa-in Palace, the former Summer Palace of Thai kings. * Bandar Puteri Puchong, a township in Puchong, Selangor, Malaysia * Beckenham Place Park, a local nature reserve in southeastern London * Belmont Provincial Park, a pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mega Ampere Spherical Tokamak
Mega Ampere Spherical Tokamak (MAST) was a nuclear fusion experiment, testing a spherical tokamak nuclear fusion reactor, and commissioned by EURATOM/UKAEA. The original MAST experiment took place at the Culham Centre for Fusion Energy, Oxfordshire, England from December 1999 to September 2013. A successor experiment called MAST Upgrade began operation in 2020. Design A spherical tokamak is shaped more like a cored apple than the conventional, doughnut-shaped toroidal design used by experiments such as ITER. Spherical tokamaks are more efficient in their use of the magnetic field. MAST included a neutral beam injector for plasma heating. It used a merging compression technique for plasma formation instead of the conventional direct induction. Merging compression saves central solenoid flux, which can then be used to increase the plasma current and/or maintain the required current flat-top. MAST's plasma volume was about 8 cubic meters. It confined plasmas with densities on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garching
Garching bei München (''Garching near Munich'') or Garching is a town in Bavaria, Germany, near Munich. It is the home of several research institutes and university departments on its campus. It became a city on 14 September 1990. Location The town is at , near the river Isar and the Bundesautobahn 9. Garching has a number of scientific research institutes and scientific experiment facilities located in the city, including a linear accelerator and a research nuclear reactor. The nuclear research reactor, nicknamed ''Atomei'' (atomic egg) appears in the city's coat of arms, and started the process leading to an accumulation of research institutes. A number of roads and places in the city are named after scientists, mathematicians and technical innovators such as Carl von Linde, Rudolf Diesel, Albert Einstein, Leonhard Euler, Werner Heisenberg, Max Planck, Wilhelm Röntgen, and Erwin Schrödinger. Districts The town has four districts: * Garching * Dirnismaning * Hochbrück * H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Max Planck Institute Of Plasma Physics
The Max Planck Institute for Plasma Physics (german: Max-Planck-Institut für Plasmaphysik, IPP) is a physics institute investigating the physical foundations of a fusion power plant. The IPP is an institute of the Max Planck Society, part of the European Atomic Energy Community, and an associated member of the Helmholtz Association. The IPP has two sites: Garching near Munich (founded 1960) and Greifswald (founded 1994), both in Germany. It owns several large devices, namely * the experimental tokamak ASDEX Upgrade (in operation since 1991) * the experimental stellarator Wendelstein 7-X (in operation since 2016) * a tandem accelerator * a high heat flux test facility (GLADIS) Furthermore it cooperates closely with the ITER, DEMO and JET projects. Scientific divisions * Tokamak Scenario Development * Plasma Edge and Wall * Stellarator Heating and Optimization * Stellarator Dynamics and Transport * Stellarator Edge and Divertor Physics * Wendelstein 7-X Operations * Stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
