Helium line ratio
Encyclopedia
The brightness of an atomic spectral line
emitted by atoms in a gas (or plasma
) can be proportional to the gas's temperature, pressure or a weighted sum of both.
Due to the completeness and accuracy of collisional radiative models for helium
the temperature and density of plasmas which have helium present can be measured by taking ratios of the emission intensities of various atomic spectral lines.
Atomic spectral line
In physics, atomic spectral lines are of two types:* An emission line is formed when an electron makes a transition from a particular discrete energy level of an atom, to a lower energy state, emitting a photon of a particular energy and wavelength...
emitted by atoms in a gas (or plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
) can be proportional to the gas's temperature, pressure or a weighted sum of both.
Due to the completeness and accuracy of collisional radiative models for helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
the temperature and density of plasmas which have helium present can be measured by taking ratios of the emission intensities of various atomic spectral lines.