inductively coupled plasmas*

The emission of vacuum ultraviolet (VUV) radiation is investigated in low-pressure Ar-O₂ inductively coupled plasmas via numerical simulations. Controlling VUV fluxes is important in a number of industrial and biomedical plasma applications because, depending on the process, VUV radiation may be desired, required to a certain degree, or unwanted. For this purpose, a self-consistent Ar-O₂ plasma-chemical reaction scheme has been implemented in a zero dimensional plasma chemistry model and is used to investigate VUV emission from excited O atoms (3s ⁵S⁰ and 3s ³S⁰) at 130 and 135 nm. The model has been successfully compared against experimental measurements of VUV emission, electron densities and excited state densities. In addition, VUV emission rates are investigated as a function of pressure, Ar-O₂ mixture, and continuous and pulsed power deposition. Moreover, the dominant reaction pathways leading to VUV emission have been identified and described. In general, when the dissociation degree of O₂ is large, VUV emission is high and is dominated by 130nm light from the decay of O(3s ³S⁰) to ground state. On the other hand, when the dissociation degree is low VUV emission rates are also low and are dominated by dissociative electron impact excitation processes.