Development of reflection gratings for advanced ECRH scenariosBurkhard Plaum, Martin Schubert, Achim Zeitler, Walter Kasparek, Carsten Lechte, Jörg Stober and ASDEX Upgrade TeamEPJ Web Conf., 203 (2019) 04012DOI: https://doi.org/10.1051/epjconf/201920304012