Seminar DPE: Waseem Khan

We cordially invite you to the lecture of a doctoral student from the Department of Physical Electronics, studying under Assoc. Prof. Pavel Dvořák:

Waseem Khan - Spatially Resolved Measurement of Ground State Atomic Nitrogen Concentration in an Argon RF Plasma Pencil using Picosecond TALIF Method

The absolute density of grounded state atomic nitrogen and the spatial dependence in the plume of atmospheric plasma jet was analyzed using the two-photon absorption laser-induced fluorescence (TALIF) method. The plasma jet is driven at radio frequency (RF) and ignited with argon gas at atmospheric pressure. The absolute density of atomic nitrogen was measured in the plume with pure argon and an admixture of nitrogen gas. The results of the TALIF measurement show that the spatial profile of absolute density was altered when nitrogen gas was added to pure argon ignited by RF discharge.

In the case of N2 admixture, most of the atomic nitrogen is found near the capillary, where the plasma starts blowing out into the atmosphere; on the other hand, in pure argon, the absolute concentration increases with distance from the capillary up to 15 mm and then decreases up to the end of the plasma plume. The average absolute concentration of atomic nitrogen (N) in pure argon discharge and with admixture of N₂ = 20 sccm and N₂ = 80 sccm was measured 6.6303 × 10¹⁶cm^-3 , 5.1298 × 10¹⁷cm^-3 and 1.1065 × 10¹⁸cm⁻³ respectively. The lifetime of atomic nitrogen in the excited state remains almost constant with increasing discharge power and independent of the position of the plasma plume.