A Buffer Pressure Effect of Charged Particle Diffusion on Photo-EMF of a Two-Chamber Cell in a Sodium–Argon Mixture

Photoplasma in Na–Ar mixtures in a two-chamber cell has been studied to generate an electromotive force (EMF) in a wide range of buffer gas pressure (0.1–100 torr). Instead of our earlier work being restricted to the situation of the Doppler profile only, the Voigt profile of the D1 and D2 resonance lines of Na has been investigated with the consideration of radiation transfer within the framework of the Biberman–Holstein approximation. The spatially uniform photoexcitation of sodium resonance levels in the first chamber has been assumed. In turn, plasma in the second chamber is created due to charge transport from the first chamber. Results of 2-D simulation show that the obtained EMF, the potential difference between the first and second chambers, can change its sign with the buffer gas pressure variation associated with the peculiarities of the change in charge transport in the cell under study. The influence of the wall potential drop in both chambers on the EMF has been investigated in detail. A limited case of the single-chamber cell has been considered, and the importance of the diffusion processes in the second chamber in forming EMF has been shown. These findings have relative influences on modeling and estimating photovoltaic converter design parameters.