Particle trapping by dusty microplasmas

Summary form only given. The highly localized potential gradients created within microplasma are capable of trapping micro- and nanoparticles. In this work, microplasma is generated within a 150 mum gap formed in a microstrip transmission line split-ring resonator. The resonator operates at 900 MHz and consumes 300 mW of power from 100 Pa to 1 atm in argon. Melamine (ML) particles are released 1 cm from the microplasma. The particles acquire a negative charge and are captured within the localized potential well of the microplasma. The residence time of particles is several minutes in flowing argon at 300 Pa. The particles are illuminated by HeNe laser and are observed to form "plasma crystals" with a periodicity of 120 microns. At low concentrations, particles are also found to move in non-decaying circular orbits with orbital radii of ~100 microns. The particle positions allow for the visualization of the microplasma sheath and can be used as a plasma diagnostic. Auxiliary electrodes consisting of quarter-wave microstrip transmission lines are used to directly modify the DC potential within the microplasma without affecting the microwave impedance within the discharge. These electrodes are used to electrostatically manipulate the suspended particles. Application of these principles to nanoparticle sensing and diagnostics will be discussed