An X-ray window including a primary and a secondary window element. In order to evaporate debris by ohmic heating, current flows through the secondary (upstream) window element. Meanwhile, electric charge originating from electron irradiation and/or depositing charged particles is to be drained off the window element. To prevent large debris particles from short-circuiting the window element and changing the desired heating pattern, the current for heating the window element flows through a layer which is insulated from the charge-drain layer.