A vacuum chamber for performing a plasma treatment comprising a plasma treatment area which is enclosed by chamber walls, and a plasma source comprising: a cathode (110, 210, 220, 310, 320, 330) for cathodic vacuum arc evaporation with an arc anode which is connected to the chamber, wherein the cathode is arranged in the chamber on the chamber wall; an electrode (120, 120a, 130, 140, 240, 250, 340, 350, 360) arranged in the chamber and spaced from the cathode (110, 210, 220, 310, 320, 330) for controlling a plasma in the vacuum chamber; characterized in that the plasma source further comprises: a shield (115, 230, 332, 333, 334) for shielding particles and metal ions which are emitted from the cathode, wherein the shield (115, 230, 332, 333, 334) is provided in the vacuum chamber in such a way that it can be arranged in front of the cathode (110, 210, 220, 310, 320, 330); and the electrode (120, 120a, 130, 140, 240, 250, 340, 350, 360) comprises a two-dimensional surface for collecting electrons emitted from the cathode (110, 210, 220, 310, 320, 330), and the two-dimensional surface has a first orthogonal extension and a second orthogonal extension to a surface normal, wherein the first orthogonal extension is perpendicular to the second orthogonal extension, wherein a length ratio of the first orthogonal extension to the second orthogonal extension is between 0.4 and 1. a cathode (110, 210, 220, 310, 320, 330) for cathodic vacuum arc evaporation with an arc anode which is connected to the chamber, wherein the cathode is arranged in the chamber on the chamber wall; an electrode (120, 120a, 130, 140, 240, 250, 340, 350, 360) arranged in the chamber and spaced from the cathode (110, 210, 220, 310, 320, 330) for controlling a plasma in the vacuum chamber; characterized in that the plasma source further comprises: a shield (115, 230, 332, 333, 334) for shielding particles and metal ions which are emitted from the cathode, wherein the shield (115, 230, 332, 333, 334) is provided in the vacuum chamber in such a way that it can be arranged in front of the cathode (110, 210, 220, 310, 320, 330); and the electrode (120, 120a, 130, 140, 240, 250, 340, 350, 360) comprises a two-dimensional surface for collecting electrons emitted from the cathode (110, 210, 220, 310, 320, 330), and the two-dimensional surface has a first orthogonal extension and a second orthogonal extension to a surface normal, wherein the first orthogonal extension is perpendicular to the second orthogonal extension, wherein a length ratio of the first orthogonal extension to the second orthogonal extension is between 0.4 and 1. a shield (115, 230, 332, 333, 334) for shielding particles and metal ions which are emitted from the cathode, wherein the shield (115, 230, 332, 333, 334) is provided in the vacuum chamber in such a way that it can be arranged in front of the cathode (110, 210, 220, 310, 320, 330); and the electrode (120, 120a, 130, 140, 240, 250, 340, 350, 360) comprises a two-dimensional surface for collecting electrons emitted from the cathode (110, 210, 220, 310, 320, 330), and the two-dimensional surface has a first orthogonal extension and a second orthogonal extension to a surface normal, wherein the first orthogonal extension is perpendicular to the second orthogonal extension, wherein a length ratio of the first orthogonal extension to the second orthogonal extension is between 0.4 and 1.