Effect of the nature of plates taped on the powered electrode on dust-particles generated in a CH4 radio-frequency discharge

William Desdions (1) , Isabelle Géraud-Grenier (1) , Francois Faubert (1) , Maxime Mikikian (1) , Véronique Massereau-Guilbaud (1)

1 GREMI - Groupe de recherches sur l'énergétique des milieux ionisés

In a capacitively-coupled radio-frequency (RF) discharge (13.56 MHz) in CH4, dust-particles are generated at low pressure (120 Pa). The gas is injected in the chamber with a flow rate of 5.6 sccm (9.45.10-3 Pa.m3.s-1). The plasma is generated between two parallel plane aluminum electrodes: the upper one is powered (80 W) by the RF generator and the lower one is grounded. An impedancemeter follows the evolution of the plasma electrical parameters. In our conditions, the dissociation of CH4 leads to the formation of dust-particles in the plasma bulk, and to the growth of a coating on the powered electrode. The dust-particles are trapped at the sheath boundary because of forces exerted on them, leading to the formation of dust-particle clouds parallel to the electrodes. When the dust-particles become too big and too heavy, they fall onto the grounded electrode, so they can be collected. The purpose of this experimental study is to understand how the nature of the powered electrode can influence the plasma parameters and the dust-particles generation. First of all, the electrodes are cleaned with ethanol and sand paper. Then, thin plates of different materials are cleaned with ethanol and taped on the powered electrode with conductive tape. 60% of the powered electrode is covered with the plate. After this, the pressure is lowered and the chamber is filled with CH4, and the plasma is turned on. After 15 minutes, the plasma is turned off. The dust-particles generated and the plates are collected in order to observe them by Scanning Electron Microscopy. The morphology of the coating formed on the powered electrode differs in function of the material of the plate. The diameter of the dust-particles and the electrical parameters of the discharge are also affected by the nature of the plate. Moreover, less dust-particles are generated when an insulator plate is taped on the powered electrode, compared to when a conductive plate is taped.

Mots clés: Dusty plasmas; Complex plasmas; Nanoparticles; Methane; Self-bias voltage

Domaines: Plasmas; Physique des plasmas [physics.plasm-ph]

William Desdions, Isabelle Géraud-Grenier, Francois Faubert, Maxime Mikikian, Véronique Massereau-Guilbaud. Effect of the nature of plates taped on the powered electrode on dust-particles generated in a CH4 radio-frequency discharge. 16th International Conference on Plasma Surface Engineering (PSE 2018), Sep 2018, Garmisch-Partenkirchen, Germany. ⟨hal-01978271⟩