Finite plasma sheath corrections applied to electrostatic probes

Langmuir or electrostatic probes are one of the oldest and yet the most widely used diagnostic in almost all fields of plasma physics research. Probe theories are, however, rather complex subject and invariably difficult to be experimentally checked with precision, even within the expected range of their validity. Testing probe theories against data from dedicated experiments using quiescent magnetized plasmas, is a very important task for assuring compatibility with the use of this diagnostic and validated models in more complex plasmas, notably those at the edge of the magnetic fusion plasmas. In these particular plasmas, attaining more precise plasma parameters directly impacts studies on a high variety of edge profile dependent phenomena, with impact in particle and heat transport and global confinement and local stability (e.g. H-mode pedestal and ELMs, respectively). It also helps to properly back-up more complex plasma edge diagnostics. The present work reports experiments to proper infer plasma parameters in low-magnetized glow discharge plasmas using electrostatic probes with different pin diameters, and operating in sweep mode. Particularly the plasma density parameter is detailed analyzed and inferred from different finite-plasma sheath theories, notably that from the non-magnetized collisioness plasma model proposed by Hutchinson.