Patent ID: 7971370

Claim:
An apparatus for treating a moving substrate of indefinite length, comprising: (a) a control surface in close proximity to a surface of the substrate to define a control gap between the substrate and the control surface; (b) a first chamber near the control surface, the first chamber having a gas introduction device; (c) a second chamber near the control surface, the second chamber having a gas withdrawal device, such that the control surface and the chambers define a region wherein the adjacent gas phases possess an amount of mass; wherein upon inducing transport of at least a portion of said mass within said region: M 1 means total net time-average mass flow per unit width into or out of the region resulting from pressure gradients, M 1 ′ means the total net time-average mass flow of a gas per unit width into the region through the first chamber from the gas introduction device, M 2 means time-average mass flow per unit width from or into at least one major surface of the substrate within the region, M 3 means total net time-average mass flow per unit width into the region resulting from motion of the substrate, and M 4 means time-average rate of mass transport through the gas withdrawal device per unit width such that M 1 +M 1 ′+M 2 +M 3 =M 4 , M 1 has a value greater than zero but not greater than 0.25 kg/second/meter and there is a slight inflow of gas into the region.