Plasma and electrical characteristics depending on an antenna position in an inductively coupled plasma with a passive resonant antenna

We investigated the plasma and electrical characteristics depending on the antenna position in an inductively coupled plasma with a passive resonant antenna. When the powered antenna and passive resonant antenna are installed near the top plate and in the middle of the cylindrical reactor (Setup A), respectively, the ion density at the resonance is about 2.4 times to 9 times higher than that at non-resonance. This is explained by the reduction in power loss in the powered antenna (including the matching circuits) and the increase in power absorbed by the plasma discharge. However, when the powered antenna and passive resonant antenna are interchanged (Setup B), the ion density at the resonance is not significantly different from that at the non-resonance. When RF power is changed from 50 W to 200 W, the ion density at the resonance of Setup B is 1.6 times to 5.4 times higher than at the non-resonance of Setup A. To analyse this difference, the profile of the z-axis ion density is measured and the electric and magnetic field simulations are investigated. The results are discussed along with the electron kinetics effect and the coupling loss between the antenna and the metal plate.

The Evolution of Collisionless Magnetic Reconnection from Electron Scales to Ion Scales

It is generally accepted that collisionless magnetic reconnection is initiated on electron scales, which is mediated by electron kinetics. In this paper, by performing a two-dimensional particle-in-cell simulation, we investigate the transition of collisionless magnetic reconnection from electron scales to ion scales in a Harris current sheet with and without a guide field. The results show that after magnetic reconnection is triggered on electron scales, the electrons are first accelerated by the reconnection electric field around the X line, and then leave away along the outflow direction. In the Harris current sheet without a guide field, the electron outflow is symmetric and directed away from the X line along the center of the current sheet, while the existence of a guide field will distort the symmetry of the electron outflow. In both cases, the high-speed electron outflow is decelerated due to the existence of the magnetic field B z , then leading to the pileup of B z . With the increase of B z , the ions are accelerated by the Lorentz force in the outflow direction, and an ion outflow at about one Alfvén speed is at last formed. In this way, collisionless magnetic reconnection is transferred from the electron scales to the ion scales.