Self-Excited Irregular Oscillation of Positively Charged Fine-Particles in Magnetized Double Plasmas

We have investigated behaviors of positively-charged fine particles in a cross-sheath between magnetized double plasmas with different potentials separated vertically by the horizontal magnetic field. In the sheath the charges on the particles become positive, because ion current flowing from a lower high-potential plasma surpasses electron current coming across the magnetic filed from an upper low-potential plasma. We have observed self-excited irregular oscillations of the positively-charged fine particles in vertical direction. In this paper, we report the characteristic property of the oscillations and discuss the mechanism of the irregular oscillation by taking account of the mutual interaction between the particles and charging processes on the particles.