距离地面200~600km之间的低地球轨道（Low Earth Orbit， LEO）空间，是对地观测卫星，气象卫星，空间站等航天器的主要运行区域，但由于地球轨道环境存在原子氧、紫外辐射、粒子辐射、高真空、等离子体、热循环以及微流星体与空间碎片的风险，对航天器的使用寿命和稳定性存在严重威胁，其中原子氧、紫外辐射、高真空、真空热循环对航天器表面材料会产生严重的损伤效应，影响材料尺寸稳定性、物理性能及机械性能。其中原子氧作为LEO环境中的主要组分，它具有很强的氧化性。当飞行器以轨道速度在LEO低地球轨道中运行时，原子氧以4~5eV的动能撞击飞行器材料表面。原子氧与材料之间的相互作用会造成表面材料剥蚀以及材料性能退化，它对有机材料的腐蚀作用还会产生可凝聚的气体生成物，进而污染航天器的光学仪器及其它设备。目前，原子氧效应研究已成为低地球轨道空间LEO环境效应研究的一个不可缺少的组成部分。
Resonance.Ltd开发的原子氧效应地面模拟实验舱，采用采用CO2激光加热分解产生原子氧束，可同时满足能量为5eV和通量为3~5×10^16 atoms/cm2/s的严苛条件，其试验结果与LEO飞行暴露试验结果符合程度很高，被认为是目前实现定性和定量进行原子氧效应地面模拟的**手段。
Description:
Resonance Ltd. has developed systems to expose spacecraft materials to thermal atomic oxygen and VUV-UV light that simulates low earth orbit conditions. Oxygen atoms are produced upstream from the exposure chamber by radio frequency dissociation of O2. Atomic oxygen concentrations to 10^15 atoms/cm^3 can be generated with the high power RFX-500 generator. This is comparable to an atomic oxygen flux of roughly
2x10^16 cm^2/sec (equivalent 5 eV atomic flux measured with
Kapton dosimeter).
The oxygen density profile across the material sample can be measured in-situ with the Resonance Ltd. Atomic Oxygen Density Profiler using the technique of resonance absorption.
Resonance also provides light sources from 30 to >1，000 nm that simulate the solar spectrum. The Atomic Oxygen Density Profiler and Solar Simulator Sources can be easily adapted to existing atomic oxygen exposure systems.
AO systems from Resonance have been used by Canadian Space
Agency， by Stanford University， University of Tokyo， Los Alamos
FEATURES:
Simulates Low Earth Orbit Erosion
Samples exposed to continuous stream of thermal Oxygen atoms
High Flux
Atomic oxygen fluxes up to 3 x 10^19 atoms/cm2/sec
Quick Turn Around
Measurable erosion of Kapton by weight loss in ? hour Typical
sample exposure time is 2 hours
Solar Simulation
Calibrated Solar simulation using VUV UV and Visible light
sources and detectors
No Interferents
Samples are downstream from active plasma and are not exposed to
uncontrolled ions， metastables or UV radiation as in plasma ashers
In-Situ Atomic Oxygen Density Profile
Atomic oxygen density profile is measured by resonance absorption
of VUV line
Thermal Controlled Sample Holder
Sample holder can be heated to increase erosion rate. Thermal- vacuum cycling of the sample is also available
