In-situ diagnostics of hydrocarbon dusty plasmas using quantum cascade laser absorption spectroscopy and mass spectrometry

The formation of carbon nanoparticles in low pressure magnetized H2/CH4 and H2/C2H2 plasmas is investigated using infrared quantum cascade laser absorption, mass spectrometry, and electrostatic probe measurements. Results showed that dust formation is correlated to the presence of a significant amount of large positively charged hydrocarbon ions. Large negative ions or neutral hydrocarbon were not observed. These results, along with a qualitative comparison of diffusion and reaction characteristic, suggest that a positive ion may contribute to the growth of nanoparticles in hydrocarbon magnetized plasmas.