The Double-Disk Diamond Window as Backup Broadband Window Solution for the DEMO Electron Cyclotron System. - Aiello, Gaetano; Gantenbein, Gerd; Jelonnek, John; Meier, Andreas; Scherer, Theo; Schreck, Sabine; Strauss, Dirk; Thumm, Manfred (Journal of Nuclear Engineering (JNE), 2022)