a lithographic projection apparatus for euv lithography includes a foil trap , or channel barrier . the foil trap forms an open structure after the source to let the radiation pass unhindered . the foil trap is configured to be rotatable around an optical axis . by rotating the foil trap , an impulse transverse to the direction of propagation of the radiation can be transferred on debris present in the beam . this debris will not pass the foil trap . in this way , the amount of debris on the optical components downstream of the foil trap is reduced . the foil trap may be alternately rotated around the optical axis in a first direction and a second direction opposite the first direction .