Atmospheric inductively coupled Ar/H$_{\mathrm{2}}$ plasma torch for spraying B$_{\mathrm{4}}$C/Cu functionally gradient material

For preparing plasma facing material (PFM) in fusion device, an Ar/H$_{\mathrm{2}}$ inductively coupled plasma torch driven by a 24-60 MHz RF power is developed for spraying B$_{\mathrm{4}}$C/Cu functionally gradient material (FGM). In previous studies, we found that by adding a fractional amount of H$_{\mathrm{2}}$ gas into Ar plasma, quality of B$_{\mathrm{4}}$C/Cu coating was significantly improved. To discuss the effect of ingredient and the flow rate of plasma gas and frequency of the RF power on plasma characteristics, the optical emission spectroscopy (OES) measurement was performed. The gas rotational temperature is determined by simulating experimental hydroxyl spectra. The excitation temperature is estimated by the ratio of the intensities of the spectral lines of Ar I based on Boltzmann's method. The effects on B$_{\mathrm{4}}$C/Cu coating quality were studied by means of X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). All the plasma properties and the results of B$_{\mathrm{4}}$C/Cu coating would give us an insight on the mechanism and the possibility of improving the process.