Corona discharges in a cylindrical coaxial arrangement were studied when well-defined voltage impulses of both polarities were applied to the axial conductor either directly or through a series gap. These comparative experiments were called the reference and the floating electrode experiment. Lichtenberg figures were recorded over photographic film that was in contact with the axial conductor. Significant differences in the visual appearance of corona and in the magnitude of the generated corona space charge between the reference experiment and the floating electrode experiment were observed. A discharge in the series gap transforms the slowly varying electric field into a rapidly rising electric field impulse in the coaxial arrangement. In this way, the space charge screening effects characteristic of a slowly varying electric field can be avoided and more space charge can be produced. During the tail part of the applied voltage impulse to the axial conductor neutralisation of the space charge by back-flashover was observed.