Maser Guide, Meaning , Facts, Information and Description
The acronym maser stands for Microwave Amplification by Stimulated Emission of Radiation. A maser resembles a laser, but operates in the microwave region of the electromagnetic spectrum.
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2 Uses 3 Technology 4 Cosmic masers |
History
Charles H. Townes, J. P. Gordon, and H. J. Zeiger built the first maser at Columbia University in 1953. The device used stimulated emission in a stream of energised ammonia molecules to produce amplification of microwaves at a frequency of 24 gigahertz.
Townes later worked with Arthur L. Schawlow to describe the principle of the optical maser, or laser, which Theodore H. Maiman first demonstrated in 1960.
Uses
Masers serve as high precision frequency references, for example as an atomic clock. They are also used as electronic amplifiers in radio telescopes.
For more information about frequency reference masers, see atomic clock.
Telescopic masers use arrays of chromium atoms in an insulating aluminium oxide crystal as amplifiers, pumping the energy in at a different radio frequency. That is, they use polished strips of synthetic ruby.
As the input signal comes in, a gold comb (made of gold because it cannot corrode and change shape) distributes it along the strip of polished ruby. As the radio wave moves through the crystal, it knocks electrons into different orbits. As the electrons wiggle into their new, lower orbits, closer to their atoms' nuclei, they add to the wave that knocked them down. A radio wave is made by a wiggling electric charge or magnetic field.
The comb-fingers are spaced so that the desired radio waves add together as they move down the crystal. This means that unwanted radio waves don't add together, and are therefore filtered out.
Technology
For cooling, masers use liquid helium at a temperature of only about 4 kelvin. This reduces the noise from electrons, nuclei, and other charged particles that the molecular motion of heat can bounce around.
The electrons are pumped away from their nuclei by longer, ignorable radio waves put onto the ruby from a different comb.
Cosmic masers
Masers also occur in nature. In interstellar space, water molecules in star-forming regions can undergo a population inversion and emit radiation at 22 GHz, creating the brightest spectral line in the radio universe. Some water masers also emit radiation from a vibrational mode at 96 GHz.
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