A direct-current (DC) plasma system for processing of a substrate, comprising: a DC plasma reaction chamber configured to contain a DC plasma that is generated between an anode (A) and a cathode (C) of the DC plasma reaction chamber ; a substrate support stage (S) arranged in a region (G3) of the DC plasma reaction chamber that contains a positive column of the DC plasma, a reference plate (R) made of a conductive material arranged in the region (G3) of the DC plasma reaction chamber that contains the positive column of the DC plasma so that a first surface potential (V R ) that develops at a surface of the reference plate (R) is equal to a second surface potential (V FP ) that develops at the surface of the substrate support stage (S), the first and second surface potentials (V R , V FP ) being based on a potential (V PP ) of the DC plasma in the positive column; and control electronics configured to measure the first surface potential (V R ) and correspondingly adjust a potential (V A ) of the anode (A) to adjust the second surface potential (V FP ) to a reference potential; and a biasing signal generator that is capacitively coupled to the substrate support stage (S), the biasing signal generator configured to generate a periodic biasing signal (V(t)) having a voltage that is referenced to the reference potential, the periodic biasing signal V(t) comprising: an active phase (ΔT BP ) having a positive voltage (V B ); a neutralization phase (ΔT BN ) having a negative voltage (V BN ); and an initialization phase (ΔT BP ) having a zero voltage. a DC plasma reaction chamber configured to contain a DC plasma that is generated between an anode (A) and a cathode (C) of the DC plasma reaction chamber ; a substrate support stage (S) arranged in a region (G3) of the DC plasma reaction chamber that contains a positive column of the DC plasma, a reference plate (R) made of a conductive material arranged in the region (G3) of the DC plasma reaction chamber that contains the positive column of the DC plasma so that a first surface potential (V R ) that develops at a surface of the reference plate (R) is equal to a second surface potential (V FP ) that develops at the surface of the substrate support stage (S), the first and second surface potentials (V R , V FP ) being based on a potential (V PP ) of the DC plasma in the positive column; and control electronics configured to measure the first surface potential (V R ) and correspondingly adjust a potential (V A ) of the anode (A) to adjust the second surface potential (V FP ) to a reference potential; and a biasing signal generator that is capacitively coupled to the substrate support stage (S), the biasing signal generator configured to generate a periodic biasing signal (V(t)) having a voltage that is referenced to the reference potential, the periodic biasing signal V(t) comprising: an active phase (ΔT BP ) having a positive voltage (V B ); a neutralization phase (ΔT BN ) having a negative voltage (V BN ); and an initialization phase (ΔT BP ) having a zero voltage. an active phase (ΔT BP ) having a positive voltage (V B ); a neutralization phase (ΔT BN ) having a negative voltage (V BN ); and an initialization phase (ΔT BP ) having a zero voltage. <EOS>