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## Current sheet
A ## Additional recommended knowledgeThe largest occurring current sheet in the Solar System is the so-called Heliospheric current sheet, which is about 10,000km thick, and extends from the Sun and out beyond the orbit of Pluto. In astrophysical plasmas such as the solar corona, current sheets may have an aspect ratio (breadth divided by thickness) as high as 100,000:1 By contrast, the pages of most books have an aspect ratio close to 2000:1. Because current sheets are so thin in comparison to their size, they are often treated as if they have zero thickness; this is a result of the simplifying assumptions of ideal MHD. In reality, no current sheet may be infinitely thin because that would require infinitely fast motion of the charge carriers whose motion causes the current. Current sheets in plasmas store energy by increasing the energy density of the magnetic field. Many plasma instabilities arise near strong current sheets, which are prone to collapse, causing magnetic reconnection and rapidly releasing the stored energy. This process is the cause of solar flares and is one reason for the difficulty of magnetic confinement fusion, which requires strong electrical currents in a hot plasma. ## Magnetic Field of an Infinite Current SheetAn infinite current sheet can be modelled as an infinite number of parallel wires all carrying the same current. Assuming each wire carries current R is a rectangular loop surrounding the current sheet. In the two sides perpendicular to the sheet, since cos(90) = 0. In the other two sides, cos(0) = 1, so if S is one parallel side of the rectangular loop of dimensions L x W, the integral simplifies to: Since The integral is evaluated: - 2
*B**L*= μ_{0}*I*_{enc}
Solving for R) as I*N*L, and simplifying:
Notably, the magnetic field strength of an infinite current sheet does not depend on the distance from it. The direction of |

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Current_sheet". A list of authors is available in Wikipedia. |