X-Nico

Langmuir probe

A Langmuir probe is a device named after Nobel Prize winning physicist Irving Langmuir, used to determine the electron temperature, electron density, and electric potential of a plasma.

•

Note that $(\backslash sqrt\{\backslash pi\}/2)\backslash langle\; v\backslash rangle\; =\; v\; p$, where$v\; p$ is the most probable velocity for the Maxwellian distribution function, so that $\backslash alpha\; =\; v\; d/v\; p$ .

•

9,10 has shown that at the Maxwellian distribution function of the electrons in a reference system moving with the velocity $v\; d$ across axis of the cylindrical probe set at plasma potential $V\; =\; 0$, the electron current on the probe can be written down in the form

•

allowing one to derive the electron energy $\backslash mathcal\{E\}\; p\; =\; kT$ (for Maxwellian distribution function only!) by a slop of the probe I-V characteristic in a semilogarithmic scale.

see also