Search

A crystallike structure was successfully formed as a result of the levitation of a kind of bacillus microorganisms $Klebsiella ~pneumoniae$ in a radio frequency (RF) plasma. The crystallike structure was confirmed to be hexagonal from top-view photograph. Neutral gas friction cools the particles down to equilibrium positions. Field Emission Scanning Electron Microscope (FE-SEM) measurement suggests that RF plasma processes the surface of levitating microorganisms. [ABSTRACT FROM AUTHOR]

We found that steady-state paired-particle motion was often observed in a fine-particle cloud in the argon plasma produced by a 100-kHz high-frequency discharge. Monodispersed spherical silica particles with a diameter of $5.0~\mu \text{m}$ were trapped in the plasma. The 2-D motion of these charged particles was carefully recorded using a microscope camera, and their orbits and perturbation frequencies were analyzed. The loci and fast Fourier transform spectra of many paired particles were obtained. By moving the camera horizontally, 3-D images of the particles were recorded, and a 3-D map of the positions of charged particles was obtained. It is considered that the forces inducing the paired-particle motion were generated by the Debye shielding and the electric field surrounding the paired particles. [ABSTRACT FROM AUTHOR]

This paper reports the levitation of micro-organisms in the sheath of radio-frequency (RF) plasma. Based on simple force-balance calculations, the required electric field for the levitation of micro-organisms has been estimated. It is predicted that micro-organisms could levitate at the periphery of the sheath. Experimental results demonstrate the levitation of two species of bacillus micro-organisms Escherichia coli (E. coli) and Klebsiella pneumoniae in an RF plasma. The almost monodiverse Klebsiella pneumoniae levitating in the RF plasma formed an ordered state similar to a 2-D Coulomb crystal. Diverse E. coli particles demonstrate the tendency that the levitating height of micro-organisms decreases as the radius of particles increases. Levitating micro-organisms in plasmas can be referred as dusty plasmas. [ABSTRACT FROM AUTHOR]

We developed a new Mie-scattering ellipsometry system for the analysis of the generation and transport of dusts in large plasma devices, such as nuclear fusion experiment devices. The system is a rotating-compensator type and consists of polarizer and analyzer modules and a 2-D image sensor. A preliminary experiment was carried out using a small dust plasma cubic chamber. Spherical divinylbenzene polymer particles of 2.25~\pm ~0.05~\mu \textm in diameter with a dispersion degree of 0.1 \mu \textm were injected and suspended in an argon plasma. Light intensity data for 1600 pixels on each image taken 30 times per second were summed as a function of compensator azimuth angle, and then, ellipsometric parameters $\Psi $ and $\Delta $ were determined through Fourier analysis and relational equations. By the comparison of the determined $\Psi $ and $\Delta $ values with the calculated ones based on the Mie theory, it can be stated that they agree fairly well with each other and the measurement method is reliable. [ABSTRACT FROM AUTHOR]