page_title: Critical ionization velocity
hierarchical_section_title: Critical ionization velocity
caption_attribution_description: English: en:Critical ionization velocity experiment onboard space shuttle Discovery (en:STS-39), releasing a plume of nitrous oxide gas.
context_page_description: Critical ionization velocity, or critical velocity, is the relative velocity between a neutral gas and plasma, at which the neutral gas will start to ionize. If more energy is supplied, the velocity of the atoms or molecules will not exceed the critical ionization velocity until the gas becomes almost fully ionized.
  The phenomenon was predicted by Swedish engineer and plasma scientist, Hannes Alfvén, in connection with his model on the origin of the Solar System. At the time, no known mechanism was available to explain the phenomenon, but the theory was subsequently demonstrated in the laboratory. Subsequent research by Brenning and Axnäs have suggested that a lower hybrid plasma instability is involved in transferring energy from the larger ions to electrons so that they have sufficient energy to ionize. Application of the theory to astronomy through a number of experiments have produced mixed results.
context_section_description: Critical ionization velocity (CIV), or critical velocity (CV), is the relative velocity between a neutral gas and plasma (an ionized gas), at which the neutral gas will start to ionize. If more energy is supplied, the velocity of the atoms or molecules will not exceed the critical ionization velocity until the gas becomes almost fully ionized.
  The phenomenon was predicted by Swedish engineer and plasma scientist, Hannes Alfvén, in connection with his model on the origin of the Solar System (1942). At the time, no known mechanism was available to explain the phenomenon, but the theory was subsequently demonstrated in the laboratory. Subsequent research by Brenning and Axnäs (1988) have suggested that a lower hybrid plasma instability is involved in transferring energy from the larger ions to electrons so that they have sufficient energy to ionize. Application of the theory to astronomy through a number of experiments have produced mixed results.
caption: Critical ionization velocity experiment onboard space shuttle Discovery (STS-39), releasing a plume of nitrous oxide gas. Full text
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