Plasma diagnostics in a double inductively coupled source (DICP) for plasma sterilisation

As a response to the need for sterilising thermolabile implant materials like polylactide or ultra-high-molecular-weight-polyethylene (UHMWPE) without toxic or water containing liquids or gases, a new kind of plasma reactor was developed. In order to achieve homogenous sterilisation efficiency, this reactor is equipped with two flat rf coils, one on top and one on bottom. Based on harmless and well-known gases like argon, hydrogen and nitrogen, good sterilisation results with Bacilus subtilis test spores have been obtained. To investigate the different plasma mechanisms necessary for the reduction of germs and spores, the plasma was analyzed by Langmuir probe (APS3) measurement, mass spectrometry and simulation. The design of the electro-polished stainless-steel chamber and the coil configuration was also based on simulation. The in-house plasma model consists on a hydrodynamic code for transport behavior and an electrodynamic part for rf coupling [Scheubert et al. J. Appl. Phys. 90(2) (2001) 587–598].