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The safety factor, labeled q or q(r), is the ratio of the times a particular magnetic field line travels around a toroidal confinement area's "long way" (toroidally) to the "short way" (poloidally). The term "safety" refers to the resulting stability of the plasma; plasmas that rotate around the torus poloidally about the same number of times ...
While the tokamak addresses the issue of plasma stability in a gross sense, plasmas are also subject to a number of dynamic instabilities. One of these, the kink instability, is strongly suppressed by the tokamak layout, a side-effect of the high safety factors of tokamaks. The lack of kinks allowed the tokamak to operate at much higher ...
An often cited description of the sawtooth relaxation is that by Kadomtsev. [2] The Kadomtsev model uses a resistive magnetohydrodynamic (MHD) description of the plasma. If the amplitude of the current density in the plasma core is high enough so that the central safety factor is below unity, a = linear eigenmode will be unstable, where is the poloidal mode number.
Tokamaks are a type of pinch machine, differing from earlier designs primarily in the amount of current in the plasma: above a certain threshold known as the safety factor, or q, the plasma is much more stable. ZETA ran at a q around 1 ⁄ 3, while experiments on tokamaks demonstrated it needs to be at least 1. Machines following this rule ...
The plasma collisionality is defined as [4] [5] =, where denotes the electron-ion collision frequency, is the major radius of the plasma, is the inverse aspect-ratio, and is the safety factor. The plasma parameters m i {\displaystyle m_{\mathrm {i} }} and T i {\displaystyle T_{\mathrm {i} }} denote, respectively, the mass and temperature of the ...
A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or aspect ratio . A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to a donut , complete with a large hole in the middle.
The Enormous Toroidal Plasma Device (ETPD) is an experimental physics device housed at the Basic Plasma Science Facility at University of California, Los Angeles (UCLA).It previously operated as the Electric Tokamak (ET) between 1999 and 2006 and was noted for being the world's largest tokamak [1] before being decommissioned due to the lack of support and funding. [2]
First plasma was obtained on NSTX on Friday, February 12, 1999 at 7:06 p.m. . Magnetic fusion experiments use plasmas composed of one or more hydrogen isotopes.For example, in 1994, PPPL's Tokamak Fusion Test Reactor produced a world-record 10.7 megawatts of fusion power from a plasma composed of equal parts of deuterium and tritium, a fuel mix likely to be used in commercial fusion power ...