Physics of the Advanced Plasma Source: a review of recent experimental and modeling approaches
Ralf Peter Brinkmann, Jens Harhausen, Benjamin Schröder, Martin Lapke, Robert Storch, Tim Styrnoll, Peter Awakowicz, Ruediger Foest, M Hannemann, D Loffhagen, Andreas Ohl
Plasma Physics and Controlled Fusion 58 014033 (2016)
The Advanced Plasma Source (APS), a gridless hot cathode glow discharge capable of generating an ion beam with an energy of up to 150 eV and a flux of 10^19/s, is a standard industrial tool for the process of plasma ion-assisted deposition (PIAD). This manuscript details the results of recent experimental and modeling work aimed at a physical understanding of the APS. A three-zone model is proposed which consists of (i) the ionization zone (the source itself) where the plasma is very dense, hot, and has a high ionization rate, (ii) the acceleration zone (of ~20 cm extension) where a strong outward-directed electric field accelerates the primary ions to a high kinetic energy, and (iii) a drift zone (the rest of the process chamber) where the emerging plasma beam is further modified by resonant charge exchange collisions that neutralize some of the energetic ions and generate, at the same time, a flux of slow ions.