DC operated gas-insulated systems play a key role in satisfying recent requirements of energy transmission. After energizing, the initial electrostatic field is changing into the electric currents field, which is determined by conductivity processes based on charge carriers. Experimental results show the temperature-dependent effects of the changed field distribution under long-term DC stress and identify clear differences to calculations, which are solely based on conventional RC models. Consequently, charge carrier based conduction processes have to be taken into account in order to calculate the transient and temperature-dependent behavior after DC switch on. This paper proves experimentally, what was solely calculated theoretically in literature so far: additional charge carriers, especially negative ions, accelerate the field transition after energizing with DC.