A self-cleaning linear ionizer with at least one ionizing electrode, at least one electrode-cleaner, and at least two spool assemblies is disclosed. The electrode has opposing ends and defines an axial working length with a surface that produces an ion cloud and develops degradation products with use. Although the working length of the electrode is stationary, the electrode is movable. The electrode-cleaner is also stationary and selectively engages the electrode along its working length. The opposing ends of the electrode are fixed to the opposing spool assemblies which selectively move the ionizing electrode such that the electrode-cleaner removes at least some of the surface degradation products from the electrode during movement. Methods of using the disclosed ionizer have self-cleaning and ionization modes of operation, which may occur cyclically, alternately, or simultaneously, are also disclosed.