POTENTIAL STRUCTURES IN ASYMMETRICAL RADIO-FREQUENCY DISCHARGES CONTAINING NEGATIVE-IONS

Potential structures in radio frequency (rf, 13.56 MHz) discharges con taining negative ions (SF6 in He gas) have been clarified experimental ly in an asymmetrical electrode system using an emissive probe. A doub le layer type potential profile is picked up near an instantaneous ano de unlike the almost flat profile in He plasma. A SF6 addition provide s a spatial shift of the double layer position toward the electrode, l owers the plasma potential, and decreases the sheath thickness. These results are ascribed to the negative ion production which is confirmed by an electrostatic analyzer measurement.