In the field of nuclear fusion technology, Er2O3 thin film is a candidate for the coating material of the blanket of thermonuclear fusion reactor. It is known that the luminescence of Er2O3 provides information on its crystallinity. We observed luminescence of Er2O3 during the irradiation with highly charged ions produced by an electron beam ion source (EBIS) as a function of charge state and kinetic energy of incident Ar ions. We found that the luminescence intensity non-linearly rises as the charge state increases and is independent of kinetic energy. This demonstrates that the luminescence of Er2O3 thin film arises from the potential energy of highly charged ions rather than the kinetic energy.
