Achieving non-contracted and non-filamentary rare-gas tubular discharges at atmospheric pressure

摘要: At gas pressures >1 kPa, tubular rare-gas electrical discharges can contract radially yielding a single axially centred bright filament. When sustaining the discharge with microwave fields of high enough frequency, instead filament, two or more smaller-diameter and off-centre plasma filaments be formed. specific percentage (<1%) rare having lower ionization potential is added to pure atmospheric-pressure discharge, single-filament contracted fully expands initially multi-filament becomes homogeneous. Experimental characteristics this phenomenon required operating conditions are reported here for first time.