In electric fields, atoms and molecules are deformed because the electrically negative atomic shell is attracted by the anode, while the positive nucleus is attracted by the cathode, gezogen werden. With a sufficiently high field strength, this can cause electrons electrons separating from their atomic or molecule compound. In this process, ions and a plasmathe substrates to remove contaminations. As the free electrons migrate to the anode and the ions (cations) move to the cathode, an electric current starts between cathode and anode. In highly diluted gases, i.e. at gas pressures of less than 10 mbar, an electrical current flow can be maintained at moderate voltages (500 - 1,000V), which results in intensive luminous phenomena. This type of gas discharges is for example used for illuminated advertising (“neon tubes“). Also refer to: ⇒ Neon tube.