Non-transferreddcarcplasmageneratorsarewidelyusedinmaterialsprocessing.Theyaregenerallyconsideredsteadily-operatingdevises.However,unsteadyphenomenadoexistinthem,andmaycausenon-idealeffectsinprocesseswhichrequirehighcontrollabilityandreproducibility.Theseunsteadyphenomenacancauseparameterfluctuationsinthearcandtheplasmajet,someofwhichhavebeenstudiedinrecentyears.Severaltypesandmechanismsofthesephenomenahavebeenidentified.Thispaperreviewst...