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The term energetic neutral atom (ENA) is used for a neutral atom, typically hydrogen, helium, oxygen, or sulfur, moving rapidly (i.e., a high kinetic energy). Typical creation in space is at the border between two clouds, where neutral atoms collide with ions. Energy can be transferred to neutral atoms or energetic ions can gain an electron in the collision. ENAs are little affected by outside forces and can travel long distances. Thus they can be used to image solar system phenomena such as the border between the ISM and the heliosphere. They can also reveal magnetic phenomena.
A different means in which a neutral atom can harbor extra energy is atomic excitation, but the term energetic neutral atom is generally used for the previous case.