Published on 2 July 2019

The Correlated Cold Matter team, led by Yan Picard and Daniel Comparat of Aimé Cotton Laboratory of Université Paris-Saclay, has developed a new method to correct the ion trajectory in real time.

Ion beams are now widely used in imaging or for the manufacture of electronic components on a scale of a few tens of nanometers. But the race towards the miniaturization of these components requires an ever-increasing resolution of the techniques. In recent years, research has focused for example on controlling the exact number of particles sent by an ion source to a target and the emission time of each particle.

Yan Picard and his colleagues of the Correlated Cold Matter team at Aimé Cotton Laboratory (CNRS/ENS Paris-Saclay/Université Paris-Sud) have extended this principle well beyond the ion source: the device they have developed makes it possible to predict the trajectory of each particle in an ion beam and to control its trajectory to a chosen location on a target.

To do this, the group of researchers generated these ions by photoionization of an atomic jet. After ionization, electron and ion are separated by an electric field. Since the electron moves about 300 times faster than the ion, it is detected at first. Based on its position, the system deducts the position of the correlated ion and predicts its future trajectory. By feedback, it adjusts in real time the electric field in which the ion moves, changes its trajectory and directs it to a previously chosen location. Only ions whose corresponding electron has been detected and validated are sent to the target, all other ions emitted by the source are systematically deflected out of the target.

Based on this concept, the team was able to focus a caesium ion beam very precisely on an axis or on a point beyond the standard performance of the electrostatic lenses used. The researchers also designed virtual diaphragms, focused the beam on several points and created virtual masks.

Usable with different types of ion sources, the technique offers new possibilities for spatial and temporal manipulation of charged particles (ions and electrons) and opens up applications in quantum technology and materials science.

A new scheme for controlling the trajectories of individual ions in a beam produced a smiley face pattern on an ion detector (left) guided by a virtual mask (right).