Influence of magnetic field on nanoparticle growth in Argon-Acetylene plasma

For over a decade, it has been hypothesized that the addition of a magnetic field can have a significant influence on the properties of a complex/dusty plasma. The Magnetized Dusty Plasma Experiment (MDPX) device at Auburn University is the most recent facility to study dusty plasmas in strongly magnetized plasmas. The MDPX device is a flexible, high magnetic field research instrument with a mission to serve as an open access, multi-user facility for the dusty plasma and basic plasma research communities. In a strong magnetic field, the transport of ions and electrons in the plasma will be modified and hence alters the whole plasma dynamics. We have experimentally investigated the influence of a magnetic field on nanoparticle growth dynamics using MDPX facility. The experiment has been performed in a capacitively coupled radio-frequency Ar/C₂H₂ discharge and the structure of the grown nanoparticles is studied ex-situ. In the absence of a magnetic field, particles are found to grow throughout the entire plasma volume and will fill the entire inter-electrode gap. By contrast, at high magnetic fields (B ≥0.5 T) the plasma, as well as the dust particles, are confined in the sheath above the grounded, lower electrode. A current channel is formed between the electrodes when the magnetic field gets stronger, which affect the growth and morphology of the nanoparticles. Moreover, at high magnetic field, large porous spherical agglomerates were formed. The study on the effect of magnetic field on particle growth help controlling the nanoparticle growth. (author)