Effect of the Electrode/Wall Area Ratio on the Plasma Potential in Discharge and Tokamak Plasmas

Plasma potential is a key parameter in plasma discharge or fusion to control plasma–wall interaction ExB drift. The magnitude of depends on the overall energy transmitted via direct current (dc) radio frequency (RF) devices such as electrodes antennas. Knowing from exciting source useful prevent high energetic fluxes wall improve confinement explaining shear velocity. aim present model calculate this with respect dc RF magnetized unmagnetized plasma. This double saturated probe (DSP) takes into account electron saturation and able derive function electrode/wall area ratio for helium/argon without magnetic field. results are compared Aanesland’s case capacitive sheath particle-in-cell (PIC) simulations. applied column perpendicular an discharge. It appears that can increase almost value at low wall/electrode ( $A_{\text {wall}}/A_{\text {el}}$ lower than 5), while same collapses soon (perpendicular over parallel area) higher electron/ion ratio. directly due current, preventing following imposed by electrode, so maximum be floating potential. involved mainly conduction modeled resistive collisional current. In plasma, rise values discharges, but collapse still occurs long biased flux tubes.