A new plasma method of synthesizing aerosol particles

A new experimental method of synthesizing aerosol particles is demonstrated. A non-thermal plasma is used to sputter a solid target by energetic ion impact. Sputtered atoms nucleate in the gas phase to form particles, which the plasma levitates particles during several hours of operation. Particle growth can take place at room temperature. The plasma is formed in a vacuum vessel by a pair of parallel electrodes that are powered with a radio-frequency high voltage. Scanning electron micrographs reveal the particle morphology. Particles initially grow with a spherical shape, and their size can be selected by terminating the discharge after they have grown to the desired diameter. By altering the plasma parameters such as gas pressure and voltage, and by allowing particles to grow for a longer period of time, they can coagulate into string-like or fractal-like conglomerates.