Boron carbide (B₄C) - due to its exceptional mechanical properties - is one of the few existing materials that can withstand the extremely high brilliance of the photon beam from free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at modern accelerator-, plasma-, or laser-based light source facilities, B₄C-coated optics are subject to ubiquitous carbon contaminations. These contaminations - that are presumably produced via cracking of CH_x and CO₂ molecules by photoelectrons emitted from the optical components - represent a serious issue for the operation of the pertinent high performance beamlines due to a severe reduction of photon flux and beam coherence, not necessarily restricted to the photon energy range of the carbon K-edge. Thus, a variety of B₄C cleaning technologies have been developed at different laboratories with varying success [1]. Here, we present a study regarding the low-pressure RF plasma cleaning of a series of carbon-contaminated B₄C test samples via an inductively coupled O₂/Ar and Ar/H₂ remote RF plasma produced using the IBSS GV10x plasma source following previous studies using the same RF plasma source [2, 3]. Results regarding the chemistry, morphology as well as other aspects of the B₄C optical coatings and surfaces before and after the plasma cleaning process are reported.

Date Published: 15 May 2017
PDF: 8 pages
Proc. SPIE 10236, Damage to VUV, EUV, and X-ray Optics VI, 102360E (15 May 2017); doi: 10.1117/12.2269374

Published in SPIE Proceedings Vol. 10236:
Damage to VUV, EUV, and X-ray Optics VI
Libor Juha; Saša Bajt; Regina Soufli, Editor(s)