Trapped dust in a low temperature plasma discharge

Home / Trapped dust in a low temperature plasma discharge

Trapped dust in a low temperature plasma discharge

This video shows the carbon dust dynamic formed in an Argon and Acetylene plasma.

The dark part in the center of the picture is the cathode of the diode plasma reactor (the anode is located below and is out of sight). We observe the carbon dust formation from C2 radicals which come from the dissociation of acetylene molecules (C2H2) in the plasma. Those dust particles measure a dozen of microns, they are electrically charged and trapped by the electric field of the cathode sheath . The asymmetry of the electric field causes counter-clockwise dust motion. When the dust agglomeration process is more advanced and dust reach a size of several hundred microns, the gravity overcomes the electric field confinement and dust fall on the anode where samples are collected and analyzed.

This video was recorded at Jean Lamour Institute (Nancy, France) in the frame of R. Hugon research work.
The analysis difficulties are multiples: first, dark dust is poorly contrasted with background whose intensity varies strongly. Second dust particles appear small (1-3 pixels) and close to each other.

Nevertheless, the TRACK software permits the analysis of the video by using pre-processing tools like the frame inversion and the auto adaptive multi-scale thresholding.