The invention relates to a plasma source (1) for depositing a coating onto a substrate (9), which is connectable to a power source (P) and includes: an electrode (2); a magnetic assembly (4) located circumferentially relative to said electrode and including a set of magnets mutually connected by a magnetic bracket (46) including a first and second central magnet (43, 44) and at least one head magnet (45); and an electrically insulating enclosure (5) arranged such as to surround the electrode and the magnets.