If these particles' density is low enough, this electrically charged gas performs differently than it would if it were neutral, and now this gas is known as plasma. The atmospheric gas concentration becomes low enough to support a plasma's specifications at about 90 kilometers above the Earth's surface. The electrons in plasma achieve more energy, and they are low in mass.
They move along the Earth's magnetic field lines, and their heightened energy is enough to escape Earth's gravity. The electrons and ions move outside of the ionosphere together. The result is that lighter ions of hydrogen, helium, and oxygen can escape from the ionosphere.
Earth possesses a strong magnetic field, so these outward moving particles stay confined near the planet unless other processes further pull them away and into interstellar space. The ionosphere is an extremely dynamic part of the atmosphere, and it expands and diminishes dependent on the energy it attracts from the sun.