Comparison of Low and High Current Density Proton Irradiation Effects on the Surface Morphology of Poly(tetrafluoroethylene)

A comparison is given about the effects of low and high current density proton irradiations on the surface topography of poly(tetrafluoroethylene). 1 MeV proton beam was used for the experiments with 10 and 10(8) pA/mm(2) current densities. For the high current density irradiations, the beam was micro-focused, while for the low current density beam it was highly under-focused. The applied ion fluences were 0.1-1000 nC/mm(2) (6.24 x 10(10)-6.24 x 10(14) ion/cm(2)). Differential interference contrast microscopy, surface profilometry, and scanning electron microscopy were used to investigate the changes of the surface morphology. It is found that at low fluences the surface is etched similarly due to low and high current density irradiations, while at high fluences thermal processes differentiate the behaviour of the surface.