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Goto, Aki*; Yamashita, Shinichi*; Kitamura, Akane; Tagawa, Masahito*
no journal, ,
Atomic oxygen (AO) is a dominant component of the residual atmosphere at low earth orbit altitude. AO collides with spacecrafts at about 8 km/s, corresponding to a translational energy of about 5 eV. It causes a critical damage such as oxidation or erosion of polymers composing the spacecrafts. A previous study has reported that nano- and microscopic needle-like protrusions were formed densely on polymer surface by AO collision. In this study, we focus on the unique morphological change because it must be useful for a modified surface. Commercial films of low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS) were irradiated with AO and their surfaces were observed by field-emission scanning electron microscopy (FE-SEM). Microscopic needle-like protrusions were formed uniformly at the surfaces of all samples, however, the uniformity decreased with increasing AO fluence due to degradation of the protrusions. The maximum protrusion density increased in the order of PP LDPE PS, showing that the density depends on the chemical structure of the polymer materials.
Ishikawa, Norito; Kondo, Keietsu; Fujimura, Yuki; Kitamura, Akane
no journal, ,
Radiation damages are induced by swift heavy ions with energy above 1 MeV/u where the energy deposition is mainly done through ionization and electronic excitation process. The previous studies of X-ray diffraction and transmission electron microscopy show that lattice expansion is induced at low fluence, and at high fluence amorphization was induced in single crystalline AlO irradiated with swift heavy ions (e.g. amorphization by irradiation with 160 MeV Xe ions at 3.510 ions/cm). Since the origin of the amorphization is still unclear, it is important to examine the irradiation-induced lattice expansion in detail.
Fukada, Yukimasa*; Fukuyama, Ryota*; Fujiwara, Kosuke*; Yoshii, Kenji; Ikeda, Naoshi*
no journal, ,