| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Tuesday Sessions |
| Session TF-TuP |
| Session: | Thin Films Poster Session |
| Presenter: | Kumiko Yokota, Kobe University, Japan |
| Authors: | K. Yokota, Kobe University, Japan T. Ohyabu, Kobe University, Japan J. Ohira, Kobe University, Japan K. Morimoto, Kobe University, Japan M. Tagawa, Kobe University, Japan |
| Correspondent: | Click to Email |
The environmental factors in space, for example, ultraviolet (including EUV and VUV wavelength), x-rays, ion and electron radiations, thermal cycling, and neutral species such as atomic oxygen (AO), give serious effects on many thin film materials used in space systems. The incompleteness of the ground-based simulation technology arises problems on the accuracy of assessment of the material survivability in real space environment. It has been reported that FEP Teflon eroded much faster in ground-based facilities than in space. This discrepancy is believed due to the ultraviolet which is a byproduct from the oxygen plasma. A laser detonation AO source, which has widely been used as a ground-based AO environmental simulator, uses high-power CO2 laser to create laser-induced oxygen plasma. The basic configuration of laser detonation AO beam source is similar to that of EUV light source using xenon gas. However, EUV from laser-detonation AO beam source has not been evaluated.
In this presentation, EUV spectra from laser-induced oxygen (and mixed gas) plasmas were reported. The flat-field EUV spectrometer especially designed for this purpose was equipped to laser-detonation AO beam source, and confirmed the capability to measure EUV spectra from oxygen plasma. Also, the cross relationship between EUV spectra, time-of-Flight (TOF) spectra of AO beam and effect of addition of Ar were investigated related to the low altitude orbital applications.
It was clearly observed that EUV emission intensity from 100%Ar plasma was greater than that from 100%O2 plasma. However, Ar emission was not observed from the laser-sustained plasma consisting of 50%Ar+50%O2 gas mixture, i.e., EUV lines only originated from oxygen were observed. Emission intensities originated from O increased with Ar content and disappeared in the pure Ar plasma. The EUV emission property was considered to be related to the collisional processes in the mixed plasma. This hypothesis was proved by the TOF spectra, i.e., dissociation reaction of O2 into AO was promoted by adding Ar in the gas. It was also observed that the EUV emission intensity decreased with increasing the supply gas pressure of the PSV. This could be a practical way to reduce the side effect of EUV on the ground-based AO simulations.
This work was supported by the Collaborative Research Support from ILE, Osaka University. A part of this research was also supported by the Grant-in-Aids for Scientific Research from JSPS under contract Nr. 25289307, 26289322, 15K14252 and 15K14253. Financial support through the Coordination Funds for Promoting Aerospace Utilization from the MEXT was also appreciated.