Particle formation in acetylene very low-pressure high density magnetized plasmas

Particle formation in cold plasmas is a matter of a large number of studies in capacitive, high-pressure, and low-density discharges. Conversely, under very-low working pressure and high plasma density conditions, as in microwave multipolar plasma excited at distributed electron cyclotron resonance (MMP-DECR), particle formation is generally not favored: the gas phase interaction probability is low due to the very-low working pressure. However, in this work, we report observations and analyses of particles formed in acetylene MMP-DECR discharges. It is proposed that the presence of the magnetic field compensates for the very-low working pressure inducing an increase in the gas phase interaction probability: negative ions are repelled by the sheath and confined within the magnetic field. Thus, particles can be formed similarly to in rf plasma. (C) 2007 American Institute of Physics.