Comparing the growth of carbonaceous and titanate dust particles in capacitively coupled RF plasmas at 500 gauss.*

Spontaneous growth of dust particles can occur when argon plasmas are mixed with reactive gases, leading to formation of dusty plasmas. As the particle growth process evolves, the particles will reach a size/mass where they can no longer be levitated against gravity and will fall out of the plasma; this leads to a cyclical growth process. In one experiment, the growth of carbonaceous particles from acetylene in argon plasmas is studied. Without a magnetic field, a growth cycle lasts ~115 seconds. However, the growth cycle is reduced to ~20 seconds in the presence of a 500 gauss magnetic field. Image analysis of the dust cloud shows that carbonaceous dust appears to be repelled by the magnetic field. In a second experiment, the growth of titanate particles from titanium tetraisopropoxide in argon plasma is studied. Here, the growth cycle is reduced from ~200 seconds (without magnetic field) to ~30 seconds (with a 500 gauss magnetic field). Image analysis of the dust cloud shows that titanate dust seems to be aligned along the magnetic field. These observations suggest that the carbonaceous and titanate dust exhibit diamagnetic and paramagnetic properties, respectively. This presentation discusses the chemical, physical, and morphological properties of dust particles.