Propagation of an Air Discharge at Atmospheric Pressure in a Capillary Glass Tube: Influence of the Tube Radius on the Discharge Structure

The experimental and simulated optical emissions of an air discharge at atmospheric pressure propagating in a capillary glass tube are compared for two tube radii: 100 and 300
$\mu\hbox{m}$
. For 300
$\mu\hbox{m}$
, both experimental and calculated optical emissions show a tubular structure of the discharge. For 100
$ \mu\hbox{m}$
, the emission of the discharge appears to be more homogeneous radially.