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--- un:magnetosphere [2024/10/06 05:48] – created asad
+++ un:magnetosphere [2024/10/06 12:49] (current) – asad
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 The outer part of the magnetotail is called the lobe. Here the electron density and temperature are very low. The electron number density is only 0.01 per cc, the temperature is 500,000 Kelvin, and the magnetic field strength is 30 nanotesla.
+===== - Magnetospheric currents =====
+The plasma in the magnetosphere is not static, moving under various external influences. Sometimes electrons and ions move together like the solar wind. But sometimes electrons and ions can move in opposite directions, and this creates electric current, which is very important for transporting charge, mass, momentum, energy, etc. in this region. The magnetic field created from this current can in turn alter the field of the magnetosphere. Some of the currents are shown in the figure below.
+{{:bn:un:magnetosphere-currents.webp?nolink&650|}}
+A current is associated with each distortion of the Earth's magnetic field. For example, the current associated with desiderite contraction flows at the surface of the magnetopause, hence the name //magnetopause current//. Similarly //tail current// flows on the surface of the nightside tail, and //neutral sheet current// on the middle plasma sheet. These tail currents and sheet currents are actually connected, and when viewed from the line joining the Earth to the Sun, their combined current looks like the Greek letter $\Theta$ .
+The inner part of the magnetosphere plays a major role in forming the //ring current//. This current flows westward around the Earth at a distance of a few Earth-radii from the Earth. Particles in the radiation belt are carriers of this current. Besides bouncing from north to south, these particles drift east-west. Protons drift west and electrons drift east, so a net transport of charge occurs.
+There are many currents in the conductive layer of the Earth's ionosphere between 100-150 km altitude. Currents worth mentioning include the auroral electrojet moving inside the auroral oval, the SQ current at mid-altitude on the Dayside, and the equatorial electrojet near the magnetic equator.
+The direction of the currents discussed so far is perpendicular to the magnetic field. But there is also current flowing along field lines. As such, the various field-aligned currents created from the flow of electrons couple the current in the magnetosphere to the current in the poleward region of the ionosphere.