Knowledge graphs (KGs) play an important role in the structured representation and linking of data, information, and knowledge. Building on the established plasma metadata schema Plasma-MDS and the plasma ontology Plasma-O, the development of Plasma-KG (https://vivo.plasma-mds.org) was initiated to represent reusable entities with persistent identifiers in the field of low-temperature plasma physics. This contribution introduces the essential concepts of Plasma-KG and of a future integration with MathModDB and MathAlgoDB, the databases and knowledge graphs for mathematical models and numerical algorithms developed by the Mathematical Research Data Initiative MaRDI (https://www.mardi4nfdi.de). This collaboration between the Leibniz Institute for Plasma Science and Technology (INP) in Greifswald and the Weierstrass Institute for Applied Analysis and Stochastics (WIAS) in Berlin has been initiated by the Leibniz MMS network.