Aluminum Implantation in Kapton® for Space Applications: Magnetic Field Effects on Implantation in Vacuum Arcs

Aluminum was implanted in samples of Kapton®, a polyimide commonly used in spacecrafts, in order to form a protective layer against degradation by atomic oxygen, abundant in space. Implantation was carried out in a vacuum-arc-generated aluminum plasma, with and without the presence of a confining magnetic field. The main effect of the magnetic field is to increase plasma density by two orders of magnitude and, as a result, the dielectric Kapton® sample should charge much faster than in the unmagnetized case. Implantation depths should therefore be larger in the unmagnetized case. Results of X-ray Photoelectron Spectroscopy depth profile analysis, however, showed similiar implantation depths in both cases, with magnetized samples having a slightly deeper and larger mixing layer. Possible mechanisms to explain this result are discussed. Both treatments resulted in an excellent protective layer as demonstrated by samples exposed to oxygen plasmas, adhesion, thermal cycling, transmission and reflectance tests.