Computer modelling of a plasma filter for evaporation and destruction of microdroplets imbedded in a plasma flow

• Applicant: Privatdozentin Dr. Iryna Litovko, Ph.D.
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525228371

Erosive sources of dense low-temperature plasma for creating ion-plasma flows (vacuum-arc type and laser-generated plasma), are used to create many types of functional coatings. They demonstrate high specific productivity but form a dusty plasma flow with the inclusion of microdroplets of the cathode material (up 60% mass), which is obstacle for applications and does not allow the formation of efficient high-quality coverage, without additional filtration and loss of original characteristics. It is especially critical for optics and microelectronics, where the presence of droplets is of fundamental nature and is a significant obstacle to obtaining high-quality films. To reduce the droplet concentration, various mechanical and electrophysical filters are used. They effectively remove droplets larger than 1 µm without significant loss of the ion-vapor flow, but their use to remove smaller droplets leads to a several times decrease in the density of the metal plasma on substrate. Thus, modern filtration methods hinder the effective use of the high rate of generation of the ion-vapor flow inherent in erosive plasma sources. Improvement of existing methods with using alternative cleaning methods can revolutionize the technologies of laser ablation and arc-plasma sputtering. One of the alternative ideas was proposed at the Institute of Physics of the NASU and consists in using the fundamental principles of plasma optics to build a filtration system that does not provide for the removal of the drop phase from the flow but, uses it as an additional source of plasma flow, so increases deposition system performance. The main idea is the effective destruction of droplets in a plasma flow passing through the system by a beam of high-energy electrons, self-consistently formed near the inner cylindrical surface of the plasma-optical system and injected along the radius towards the axis, that is underlies the proposed project. The objectives of the project will be an in-depth theoretical consideration of the flow of dusty plasma in systems of complex geometric configuration, computer simulation and identification of optimal conditions for introducing additional energy into the plasma flow to destroy droplets present in it. It is planned to carry out analytical calculations and numerical simulation of the flow of a dusty plasma flow through plasma-optical system in order to determine scientifically based conclusions that are important for creating a plasma filter for obtaining high-quality functional coatings. Modeling is supposed to be carried out for two systems with fast electrons: a system based on an electrostatic plasma lens and a magnetron-type discharge in ExH fields, and a system with a hollow cathode and trapped electrons oscillating between the cathode walls. If successful, such principle of "filtering" the plasma flow will make it possible to obtain high-quality coatings of any thickness without losing the productivity of the technological process.

• DFG Programme: WBP Position