Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N 2 - Korolov, I; Leimkühler, M; Böke, M; Donkó, Z; Schulz-von der Gathen, V; Bischoff, L; Hübner, G; Hartmann, P; Gans, T; Liu, Yue; Mussenbrock, T; Schulze, Julian (Journal of Physics D: Applied Physics, 2020)