Eurofusion

Enabling research Project

New dielectric functional materials and interfaces (DFMI) — Theoretical and Experimental analysis (2024-2025)

PI — A.I. Popov


Polycrystalline diamond disks with a respectable size of several tens of millimetres up to 180 mm produced by plasma assisted chemical vapour deposition (PACVD) in a microwave reactor are state of the art in functional optical and dielectric windows. Diagnostics and heating and current drive systems need these components as filters for well-defined frequency bands in IR, UV, VIS, Microwaves and sub-millimetre waves (THz-range) and as window materials for transmission of low and high power electromagnetic waves. In the previous enabling research projects AETA and DDRM only a few number of functional materials (FM) in relation to primary radiation defects (vacancies, F-type centres, trapped holes on cation vacancies, etc.) were investigated. Especially in diamond the influence of defect structures (nitrogen, hydrogen and oxygen) to optical and dielectric material properties were considered. For systems in plasma diagnostics, doping in diamond (Boron) has a strong influence on the optical transmission and the electrical properties of such filters and windows and even for detector applications in plasma diagnostics. Theoretical and experimental studies will explain  the mechanisms of absorption and emission in different spectral ranges depending on the dopant and the defect concentrations. The nitrogen content in diamond can have e.g. a compensation or amplification effect to the dopant concentrations in diamond. To determine experimentally the defect influences, different spectroscopic and magnetic methods (EPR, ODMR, RAMAN, IR, UV) will be used.

Theoretical calculations of the properties by using first-principle methods are foreseen to substantiate the experimental results.

A second part of the project is irradiation of doped diamond and the corresponding defect development. Irradiation with neutrons and heavy ions will show the behaviour under harsh conditions like in a fusion reactor. These properties due to transmutation effects in Boron-doped diamond systems can be used for dosimetry applications in diagnostics.