The increase of electron density in ECR ion sources assures efficient ionization of very low-gas-pressure plasma. The purpose of this experiment was the creation of a carbon nanotubes based electron gun, in order to inject electrons in the plasma core and to follow how the charge state distribution and the X-ray spectra change. The use of carbon nanotubes leads to an increase of the plasma density and to a relevant reduction of the number of high energy electrons, which are detrimental for the reliability of the modern ECRIS.