Formation of multiple Double Layers in the presence of grounded ring in RF expanding plasma

• Published in: Physics letters. A 2023-09, Vol.481, p.129016, Article 129016
• Main Authors: Saha, P.K., Chakraborty, M., Dutta, D., Sharma, N., Mukherjee, A.
• Format: Article
• Language: English
• Subjects: Multiple Double Layer structures; PIC simulation; Potential well; RF plasma expansion
• ISSN: 0375-9601
• DOI: 10.1016/j.physleta.2023.129016

Multiple potential drops have been observed in the presence of a thick grounded ring when Argon plasma is allowed to expand in a Helicon Plasma Source (HeliPS) setup. Potential drops of 18 V and 11 V have been detected at 7 × 10−4 mBar working pressure and 500 G magnetic field in the expansion region of the setup. With the increase of working pressure, the potential drop decreases exponentially obeying Boltzmann's expansion rules. After both potential drops, the plasma potential increases again and forms a potential well like structure. This experimental study has been verified with Particle In Cell (PIC) computer simulation. •The experiment on Double Layer reported here by using a grounded ring present between the source and the expansion chamber.•Rapid potential drops and potential well like structures make this experiment different from earlier observations.•High and low energetic electrons are observed in the upstream and downstream regions.•PIC simulation is done for the experimental chamber's configuration.•PIC simulation results confirm the experimental observations.