A plasma source intended for depositing a coating on a substrate and adapted to be connected to a source of energy comprising: a) an electrode delimiting a discharge cavity opening onto an aperture facing which said substrate may be positioned, the cross-section of said electrode comprising a first and a second side wall (21, 22) located on either side of a bottom (23, 24) having a central portion protruding into said discharge cavity, said central portion comprising a first and a second central wall (26, 27) and a top connecting both central walls, b) a magnetic set located at the periphery of said electrode and comprising a set of magnets connected together through a magnetic support, each of said magnets comprising an exposed pole turned towards the discharge cavity and a protected pole oriented towards said magnetic support, said set of magnets comprising: i. at least one first and one second side magnet (41,42), said first side magnet, respectively second side magnet, being positioned behind said first side wall, respectively second side wall, in proximity to said aperture, said both side magnets being oriented in such a way that their exposed poles are of the same polarity, ii. at least one first and one second central magnet (43, 44), said first central magnet, respectively second central magnet, being positioned behind said first central wall, respectively second central wall, said that both central magnets being oriented in such a way that their exposed pole is of reverse polarity to that of the exposed poles of the side magnets (41,42), iii. at least one head magnet, positioned behind said top and oriented in such a way that its exposed pole is of the same polarity as that of the exposed poles of the side magnets (41,42), c) an electrically insulating chamber laid out so as to surround the electrode and the magnets without blocking said aperture. a) an electrode delimiting a discharge cavity opening onto an aperture facing which said substrate may be positioned, the cross-section of said electrode comprising a first and a second side wall (21, 22) located on either side of a bottom (23, 24) having a central portion protruding into said discharge cavity, said central portion comprising a first and a second central wall (26, 27) and a top connecting both central walls, b) a magnetic set located at the periphery of said electrode and comprising a set of magnets connected together through a magnetic support, each of said magnets comprising an exposed pole turned towards the discharge cavity and a protected pole oriented towards said magnetic support, said set of magnets comprising: i. at least one first and one second side magnet (41,42), said first side magnet, respectively second side magnet, being positioned behind said first side wall, respectively second side wall, in proximity to said aperture, said both side magnets being oriented in such a way that their exposed poles are of the same polarity, ii. at least one first and one second central magnet (43, 44), said first central magnet, respectively second central magnet, being positioned behind said first central wall, respectively second central wall, said that both central magnets being oriented in such a way that their exposed pole is of reverse polarity to that of the exposed poles of the side magnets (41,42), iii. at least one head magnet, positioned behind said top and oriented in such a way that its exposed pole is of the same polarity as that of the exposed poles of the side magnets (41,42), i. at least one first and one second side magnet (41,42), said first side magnet, respectively second side magnet, being positioned behind said first side wall, respectively second side wall, in proximity to said aperture, said both side magnets being oriented in such a way that their exposed poles are of the same polarity, ii. at least one first and one second central magnet (43, 44), said first central magnet, respectively second central magnet, being positioned behind said first central wall, respectively second central wall, said that both central magnets being oriented in such a way that their exposed pole is of reverse polarity to that of the exposed poles of the side magnets (41,42), iii. at least one head magnet, positioned behind said top and oriented in such a way that its exposed pole is of the same polarity as that of the exposed poles of the side magnets (41,42), c) an electrically insulating chamber laid out so as to surround the electrode and the magnets without blocking said aperture.