An arrangement including an air conveying device and a suction device guiding an air flow across a site for a duration of a process. The direction of air flowing towards the surface and a tangent to the surface at the ablation site intersect at an angle. A flow velocity of the air flow is controlled. A direction of air flowing away from the surface and the tangent at the site intersect. The flow velocity is selectable, within a specified range. A flow velocity is variable.
