Motivation

The research group Reactive Flows and Diagnostics (RSM) focuses on optical investigations of reactive flows. One of the applied diagnostic techniques is Laser-Induced Breakdown Spectroscopy (LIBS), which is used within the scope of the Clean Circles project to investigate a CO₂-free, iron-based energy storage cycle. As the share of renewable energies continues to grow, storage systems with high energy density and long discharge durations are becoming increasingly important. In the Clean Circles process, renewable energy is stored by reducing iron oxide particles. The resulting metallic iron can then release energy through thermochemical oxidation (i.e., combustion of iron) in a spatially and temporally decoupled manner.

To gain a deeper understanding of the mechanisms during reduction and oxidation, and to validate and improve corresponding numerical models, experimental data are required. For this purpose, the elemental composition of burning iron particles is to be investigated using Laser-Induced Breakdown Spectroscopy (LIBS).

Tasks

In previous work, a LIBS measurement system including an electrodynamic levitator for studying individual airborne particles has already been developed and commissioned. Building on this, the goal of this thesis is to develop and implement a laser-based ignition system for the controlled combustion of suspended particles. The following tasks are planned:

• Literature review and familiarization with the ignition of metallic particles
• Setup and commissioning of a fiber laser, including dual-side beam delivery into the electrodynamic levitator and precise alignment with the levitated particles
• Development of a temporal control system in LabVIEW for accurate laser triggering and shut-off
• Integration of an ignition detection unit (consisting of two photomultiplier tubes) to detect the exact ignition time and use it as a trigger signal
• Execution of parameter studies with varying laser settings to determine optimal ignition conditions
• Evaluation and documentation of the measurement results

The thesis can be carried out either as a Master or Bachelorthesis, depending on the depth and scope.