What is extreme UV?
Extreme ultraviolet (EUV) radiation is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays. EUV is produced by high-energy events such as nuclear fusion and radioactive decay, and is thus present in the Sun’s corona and in various astronomical objects. It can also be generated artificially using synchrotron sources and ferromagnetic lenses.
EUV radiation is absorbed by Earth’s atmosphere, making it impossible to observe from the ground. However, several space telescopes have been launched that are capable of observing EUV emission from astronomical objects. These include the Hinode spacecraft, which observed the Sun’s EUV output in detail; NASA’s Solar Dynamics Observatory (SDO), which observes the Sun at all wavelengths including EUV; and the Japanese Space Agency’s ASTRO-H mission, which observed cosmic X-ray sources in EUV.
The study of extreme ultraviolet radiation is important for understanding astrophysical phenomena such as stellar coronae, accretion disks around black holes, and intergalactic gas. In addition, because EUV photons are energetic enough to ionize atoms, this type of radiation can be used for applications such as cancer treatment and material processing.
What are the properties of extreme UV?
Extreme ultraviolet radiation has a wavelength range of 10 to 121 nanometers (nm). This corresponds to a photon energy range of 12 to 124 electron volts (eV). The highest energies in this range are known as vacuum ultraviolet or VUV photons, while those at the lower end are called soft X-rays. Most astronomical objects emit more EUV photons than VUV photons; however, some objects like white dwarf stars can emit predominantly in the VUV regime.
EUV emission is strongly attenuated by Earth’s atmosphere; therefore ground-based telescopes cannot be used to observe this type of radiation directly. However, several satellites have been launched that are designed specifically for observing astronomical objects in EUV wavelengths. These include Hinode , SDO ,and ASTRO-H .
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