Related Experiment Video
Updated: Aug 11, 2026

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses
Published on: July 2, 2012
Discrete focusing effect of positive ions by a plasma-sheath lens
1Nagoya University, Department of Electrical Engineering and Computer Science, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Abstract:
We demonstrate that the sheath created adjacent to the surface of a negatively biased electrode that interfaces an insulator acts as a lens that focuses the positive ions to distinct regions on the surface. Thus, the positive ion flux is discrete, leading to the formation of a passive surface, of no ion impact, near the edge and an active surface at the center. Trajectories of positive ions within the sheath are obtained by solving in three dimensions the Poisson equation for electrodes of different geometry. Simulations are confirmed by developing the ion flux profile on the electrode surface as the sputtering pattern produced by ion impact. Measurements are performed in a dc plasma produced in Ar gas.
Related Concept Videos
Electric Field of a Charged Disk
The system's symmetry is in the cylindrical directions across the plane of the charge. As a result, the electric fields created by various surface charge elements nullify each other in the direction parallel to the surface. Thereby, the resulting electric field is perpendicular to the plane. Since the disk is...
Potential Due to a Polarized Object
Inductively Coupled Plasma–Mass Spectrometry (ICP–MS): Overview
Inductively Coupled Plasma Atomic Emission Spectroscopy: Principle
The ions and electrons produced interact with the fluctuating magnetic field created by a water-cooled...
Focusing of Light in the Eye
The Electrical Double Layer

