Charged Particle Motion in Earth's Magnetosphere

Magnetic Mirroring and the Loss Cone

A particle's pitch angle increases as it moves into a region of stronger magnetic field and decreases as it moves into a region of weaker field.

In a simple magnetic mirror geometry the magnetic field reaches a minimum value at the center of the geometry and a maximum value at the end. Particles within such a geometry can follow a range of trajectories, as described below.

stuck in the center

A particle with pitch angle cannot move into a region of stronger magnetic field, so a particle with (at the center of the magnetic mirror, where B = Bmin) cannot move away from the center of the mirror.

straight and narrow

On the other hand, a particle with pitch angle is free to move anywhere and readily travels out of the magnetic mirror.

trapped in the mirror

In a magnetic mirror geometry, particles with pitch angles in the following range are trapped within the magnetic mirror:

into the loss cone

However, particles with are said to be in the loss cone and can escape the magnetic mirror.

Last modified May 16, 2005 by Randy Russell.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Charged Particle Motion in Earth's Magnetosphere

Motions within Earth's metallic core generate the planet's global magnetic field. This magnetic field extends beyond Earth's surface and atmosphere into the space surrounding our home planet. The interaction...more

Altocumulus

Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part...more

Altostratus

Altostratus clouds (weather symbol - As) consist of water and some ice crystals. They belong to the Middle Cloud group (2000-7000m up). An altostratus cloud usually covers the whole sky and has a gray...more

Cirrocumulus

Cirrocumulus clouds (weather symbol - Cc) are composed primarily of ice crystals and belong to the High Cloud group (5000-13000m). They are small rounded puffs that usually appear in long rows. Cirrocumulus...more

Cirrostratus

Cirrostratus (weather symbol - Cs) clouds consist almost entirely of ice crystals and belong to the High Cloud (5000-13000m) group. They are sheetlike thin clouds that usually cover the entire sky. The...more

Cirrus

Cirrus (weather symbol - Ci) clouds are the most common of the High Cloud (5000-13000m) group. They are composed entirely of ice and consist of long, thin, wispy streamers. They are commonly known as...more

Cumulonimbus

Cumulonimbus (weather symbol - Cb) clouds belong to the Clouds with Vertical Growth group. They are generally known as thunderstorm clouds. A cumulonimbus cloud can grow to such heights that it actually...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA