In this paper the physics of deep plasma expansion in the rarefied regime is studied in the framework of fast deposition, surface modification and molecule conversion. A large plasma flow, produced in a cascade arc plasma source, expands into a low pressure background. The density, temperature and velocity evolution are studied with laser scattering and fluorescence techniques. The velocity distribution functions are measured, and can accurately be described by a bimodal distribution. This bimodal velocity distribution function is interpreted in terms of an unchanged expanding component that is gradually converted into a slower component by collisions with molecules or atoms from outside the barrelshock. These particles can enter the expansion due to the rarefied conditions.
|Title of host publication||Proceedings of the 24th International Symposium on Rarefied Gas Dynamics, 10-16 July 2004, Bari, Italy|
|Publication status||Published - 2005|
|Name||AIP Conference Proceedings|