Experimental investigation on the instability of the positivecolumn in oxygen (poster)

In the contribution for the first time is started the common investigation on the instability ranges of the oxygen positive column and its correlation with the density of O- ions. The ranges of the discharge stability / instability have been recorded by a linear photo diode array. The O- ion densities were measured by selective laser photo detachment in combination with the probe diagnostics. The measurements were realized in the d.c. positive column (tube diameter: 50 mm, electrode distance: 600 mm, pressure range: 0.3 Torr to 0.7 Torr, current range: 1 mA to 50 mA). The electric field strength in the H- and T- mode of the column as well as the density and energy of electrons have been estimated, too.