Langmuir probe
![One of two Langmuir probes from the Swedish Institute of Space Physics in Uppsala on board ESA's space vehicle Rosetta, due for a comet. The probe is the spherical part, 50 mm in diameter and made from titanium with a surface coating of titanium nitride.](/Images/godic/202501/23/Rosetta_Langmuir_Probe4003.jpg")
![Fig. 1. Illustration to Langmuir Probe I-V Characteristic Derivation](/Images/godic/202501/23/lossy-page1-220px-ShunkoLPFig01W.tif4003.jpg")
![Fig. 2. I-V Characteristic of Langmuir Probe in Isotropic Plasma](/Images/godic/202501/23/lossy-page1-220px-IV_Ar_0.058_370_z12.tif4003.jpg")
![Fig.3. I-V Characteristic of the cylindrical probe in crossing electron wind](/Images/godic/202501/23/lossy-page1-220px-CylinderProbeInElectrWind.tif4003.jpg")
A Langmuir probe is a device used to determine the electron temperature, electron density, and electric potential of a plasma. It works by inserting one or more electrodes into a plasma, with a constant or time-varying electric potential between the various electrodes or between them and the surrounding vessel. The measured currents and potentials in this system allow the determination of the physical properties of the plasma.