J. Blažek

Surfatron Plasma Source Working at Frequency 2.45 GHz for Technological Applications

Plasma as an active medium is widely exploited in technological applications. We have developed a microwave plasma source which might be suitable for future technological application. Plasma is generated by commercial (Sairem) surfatron working at frequency 2.45 GHz. The surfatron is fed by microwave power in the range from several watts up to 300 watts. Plasma is created from working gas mixture; typical flow rate is kept constant at 600 sccm. Technical Ar is used as carrier gas, O2 or N2 as reactive gases. We present complex diagnostics of the plasma created by this plasma source: by means of Langmuir probe measurements and by optical emission spectroscopy. Single probe method was used for determination of basic plasma parameters (plasma potential Vpl, mean electron energy Em, electron density ne, electron temperature) at low pressures. For determination of electron temperature at higher pressures when ion‐neutral collision processes in the probe sheath had to be taken into account the double probe meth...

Computer modeling of in terferograms of flowing plasma and determination of the phase shift

Interferograms of the flowing gas contain information about the phase shift between the object and the reference beams. The determination of the phase shift is the first step in getting information about the inner distribution of the density in cylindrically symmetric discharges. Slightly modified Takeda method based on the Fourier transformation is applied to determine the phase information from the interferogram. The least squares spline approximation is used for approximation and smoothing intensity profiles. At the same time, cubic splines with their end-knots conditions naturally realize “hanning windows” eliminating unwanted edge effects. For the purpose of numerical testing of the method, we developed a code that for a density given in advance reconstructs the corresponding interferogram.