From Wikipedia, the free encyclopedia Plasma parameters
Plasma parameters
Frequencies
• , the angular frequency of the circular motion of an
electron in the plane perpendicular to the magnetic
field:
• , the angular frequency of the circular motion of an
ion in the plane perpendicular to the magnetic field:
• , the frequency with which electrons oscillate
(plasma oscillation):
• :
• :
• :
• :
The complex self-constricting magnetic field lines and current
paths in a Birkeland current that may develop in a plasma
(Evolution of the Solar System, 1976) • :
Plasma parameters define various characteristics of a
plasma, an electrically conductive collection of charged
Lengths
particles that responds collectively to electromagnetic
forces. Plasma typically takes the form of neutral gas-like • , approximate average de Broglie wavelength of
clouds or charged ion beams, but may also include dust electrons in a plasma:
and grains. [1] The behaviour of such particle systems can
be studied statistically. [2]
Fundamental plasma parame- • , the closest that two particles with the elementary
charge come to each other if they approach head-on
ters and each have a velocity typical of the temperature,
ignoring quantum-mechanical effects:
All quantities are in Gaussian cgs units except tempera-
ture expressed in eV and ion mass expressed in units of
the proton mass μ = mi / mp; Z is charge state; k is Boltz-
mann’s constant; K is wavelength; γ is the adiabatic in- • , the radius of the circular motion of an electron in
dex; ln Λ is the Coulomb logarithm. the plane perpendicular to the magnetic field:
1
From Wikipedia, the free encyclopedia Plasma parameters
• , the radius of the circular motion of an ion in the
plane perpendicular to the magnetic field:
• , the depth in a plasma to which electromagnetic
radiation can penetrate:
• , the scale over which electric fields are screened out
by a redistribution of the electrons:
A ’sun in a test tube’. The Farnsworth-Hirsch Fusor during op-
eration in so called "star mode" characterized by "rays" of
Velocities glowing plasma which appear to emanate from the gaps in the
• , typical velocity of an electron in a Maxwell- inner grid.
Boltzmann distribution:
• electron plasma/gyrofrequency ratio
• , typical velocity of an ion in a Maxwell-Boltzmann
distribution:
• ion plasma/gyrofrequency ratio
• , the speed of the longitudinal waves resulting from
the mass of the ions and the pressure of the • thermal/magnetic pressure ratio ("beta")
electrons:
• magnetic/ion rest energy ratio
• , the speed of the waves resulting from the mass of
the ions and the restoring force of the magnetic
field:
References
Dimensionless • NRL Plasma Formulary (esp. p. 28 and p. 29), J.D.
Huba, Naval Research Laboratory (2007)
• square root of electron/proton mass ratio
Footnotes
• number of particles in a Debye sphere [1] Peratt, Anthony, Physics of the Plasma Universe
(1992);
[2] Parks, George K., Physics of Space Plasmas (2004,
2nd Ed.)
• Alfvén velocity/speed of light
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Categories:
• Plasma physics
• Astrophysics
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