Plasma Parameters Widget - Web Only Version

Widget version represented: 3.1

This is the web based example of the Dashboard widget for Mac OSX (Tiger). The code is directly copied from the widget version that is referenced above. This means that some functions and features of the widget may not display depending on the browser you are using.

The units of each parameter should be displayed when you hover the mouse over the parameter. For example, hovering the mouse over "Bo =" should reveal a small box that says "Magnetic Field (Gauss)". This should work on all newer browsers, including those mentioned below. In case you cannot see the units: Bo -> Gauss, ne -> cm-3, temperatures -> eV, and all output values are meters, Hertz, or unitless.

Links: Home

Browser Notes:

Bo =
ne =
μ =
Te =
Z =
Ti =
γ =
ln(Λ) =
fce =
fci =
fpe =
fpi =
νe =
νi =
re =
ri =
vthe =
vthi =
δp =
Cs =
vA =
λD =
β =
ι =

About the
Plasma Parameters Widget
version 3.1 beta

Written 2006 by David Pace

This widget brings the usefulness of the Naval Research Laboratory (NRL) Plasma Formulary to your fingertips. Providing a few basic parameters of the plasma is enough to determine fifteen different length, frequency, and velocity properties.

The following is a list of the expressions provided in the 2002 NRL Formulary. The actual output values have been multiplied by the necessary factors to put them in the units shown on the front side. Notice that while the output values are expressed in Hertz and meters where possible, the input electron density is still in cm-3 because that is the predominant unit in plasma physics.

Additional Notes:

The speed of light is given by c = 3.0 x 108 m/s.

There is no input for the ion density because all of the calculations assume quasi-neutrality. The ion density is returned as the electron density divided by the charge factor, Z.

When density and/or temperature are referenced without subscript, the value is determined by adding the contributions from the ions and the electrons. For example: T = Ti + Te

The Coulomb logarithm is provided as ln(Λ) = 12 in a default that is displayed upon opening the widget. This is a parameter that depends on the collisionality of your system. If you do not know what value to use, then it is acceptable to leave it at the default (the approximate full range is ln(Λ) between 10 and 20).

The adiabatic (polytropic) index, written as γ in the equation for the ion sound speed, is defaulted to unity but can be adjusted as the user sees fit.


I would like to thank Brian Brugman, Troy Carter, Neal Crocker, and Anne White from the UCLA Plasma Physics Group for their contributions to this widget. Additional thanks to Thomas Pedersen from Columbia University for pointing out errors in some of the calculations.

Thank you to Joe Huba from NRL for allowing me to include the official formulary link and suggesting that space plasmas receive better treatment in the output. He further suggested the inclusion of the ion inertial length, ι, and provided the expression for it.

Thank you to Aaron Roberts and Melvyn Goldstein from NASA for providing the Solar Wind parameters and seconding the request for better handling of space plasma parameters. Melvyn also demonstrated the usefulness of including the adiabatic index as an input parameter.