Laser induced fluorescence in the plasma wind tunnels

A big part of our knowledge of the structure of atoms or molecules is being provided by laserdiagnostic measurement methods. Laser-based techniques offer the capability for nonintrusive, spatially and temporally resolved measurements of a host of important erosion parameters. The interaction between electromagnetic radiation and particles leads to absorption or emission spectras, from which one can extract informations about the behaviour of species under investigation. It is of basic interest for further developments, that chemical processes of thermal protection materials are well examined and understood. The method of laser induced fluorescence can make a contribution to this objective. It offers the possibility to investigate species under interest in a selective way, just by choosing the appropriate wavelength. Fluorescence is the emission of light from an atom or molecule following promotion to an excited state by photon absorption. At the Institute for Space Systems, in cooperation with the Institute for Thermodynamics, is a laser system available to experimentally examine plasma beams and thermal protection materials as well as supersonic flows. This work is funded by the Deutsche Forschungsgesellschaft in a special research program (SFB 259). The laser system consists of an excimer laser Lambda Physik COMPex201, a dye laser Lambda Physik SCANmate 2E and a second harmonic generator to doubble the frequency. It is possible to obtain wavelengths from around 200 nanometers up to 1050 nanometers by choosing the desired dye.

Schematic LIF setup at the plasma wind tunnel PWK-2

Objectives of the project „LIF in the plasma wind tunnels of IRS"	With species under investigation:
Determination of density distributions. Determination of rotational and translational temperatures. Determination of particle velocity.	nitrogen oxide NO silicon oxide SiO atomic nitrogen N atomic oxygen O

The tests are mainly carried out at the IRS plasma wind tunnel 2 . Furthermore, there is also a special interest to measure the electric fields within the inductive heated plasma generator IPG.	Working at the LIF setup
For further informations please contact Stefan Löhle