Debris mitigation system with improved gas distribution

1. A debris mitigation system comprising a debris mitigation unit including a foil trap, said debris mitigation unit having passages allowing a straight passage of radiation, and one or several feed pipes for gas supply of a buffer gas to said debris mitigation unit, wherein said debris mitigation unit has an interior space extending over several of said passages and wherein said feed pipes open into said interior space via outlet portions, wherein said foil trap comprises a plurality of foils extending in a radial direction from a central axis, and said interior space is formed by openings in said plurality of foils that are aligned with each other to form a circumferential gas flow channel for flow of the buffer gas in the circumferential gas flow channel in a circumferential direction around said central axis, and wherein at least one outlet portion of said outlet portions of said feed pipes includes a first part and a second part which are located in the circumferential gas flow channel, the second part being perpendicular to the first part to enhance the flow of the buffer gas in the circumferential gas flow channel in the circumferential direction.

2. The debris mitigation system according to claim 1 , wherein said debris mitigation unit has essentially rotational symmetry about said central axis.

3. The debris mitigation system according to claim 1 , wherein said interior space further forms connection channels extending in the radial direction and connecting said one or several openings to said circumferential gas flow channel.

4. The debris mitigation system according to claim 2 , wherein said debris mitigation unit is mounted rotatably around said central axis.