Electron cyclotron resonance (ECR) coaxial plasma source AURA-WAVE (Sairem):
\n- microwave frequency excitation 2.45 GHz
\n- applied power range 100 \u2013 150 W
\n- chamber wall temperature varied in the range of 20\u00b0 \u2013 100\u00b0C
\n- volume of the plasma reactor about 80 l
Hydrogen with dilution of nitrogen in the range of 0, 500, 1000, 1500, 2500 and 5000 ppm respectively. Total flow rate of 14 sccm is kept constant. Pressure was varied in the range of 3 \u2013 7 Pa.
\n" }, "target": [], "diagnostics": { "name": "TALIF", "properties": "Two-photon absorption laser induced \ufb02uorescence (TALIF) for the detection of hydrogen atoms. For this photons with a wavelength of 205 nm are created through the combination of a frequency doubled Nd:YAG pump laser (Spectra Physics, Quanta Ray), with a pulse width of 6 ns, and with a dye laser (Sirah, Precision Scan SL). The 615 nm red light from the dye laser is frequency doubled with the help of a BBO crystal, and then remixed with residual red light from the dye laser in a second BBO crystal for sum-frequency generation to the required 205 nm radiation.
\n", "procedure": "For the detection of the fluorescence a Nikon lens systems was used to image a region of interest of about 10 and 2 mm in the horizontal and vertical distances respectively. As a detector a gateable ccd camera was used (Andor iStar DH734x) in combination with a spectral filter providing a bandwidth of 10 nm centered at around 656 nm for hydrogen and 825 nm for krypton respectively.
\nThe absolute atomic hydrogen densities could be derived from the fluorescence by calibrating the appropriate fluorescence using krypton.