Lithographic apparatus and method in a lithographic process

A method in a lithographic process, the method comprising:

• performing relative movement between of a first component and second component, wherein the first component has a first surface, the second component has a second surface and the first surface and the second surface face each other;
• and
• providing a barrier operative to reduce or prevent an inflow of ambient gas into a protected volume of gas between the first surface and the second surface, wherein providing the barrier comprises:
• providing a flow of curtain gas from at least one curtain opening accommodated by the first surface so as to establish a gas curtain enclosing part of the protected volume adjacent the first surface;
• and
• providing a flow of inner entrainment gas from at least one inner entrainment opening accommodated by the first surface for being entrained into the flow of curtain gas,
• wherein the flow of inner entrainment gas is less turbulent than the flow of curtain gas, and
• wherein the at least one inner entrainment opening is radially inward of the at least one curtain opening with respect to the protected volume.

An apparatus comprising:

• a first component having a first surface;
• and
• a second component having a second surface, wherein, in a use;
• the first surface faces the second surface and wherein a relative movement can be provided between the first and second components;
• a gas curtain opening, located at the first surface, configured to provide a flow of curtain gas to establish a gas curtain configured to enclose part of a protected volume of gas between the first and second surfaces and to reduce or prevent an inflow of ambient gas into the protected volume of gas;
• and
• an inner entrainment opening, located inward of the gas curtain opening relative to the protected volume, configured to provide a flow of inner entrainment gas for being entrained into the flow of curtain gas,
• wherein the apparatus is configured such that the flow of inner entrainment gas is less turbulent than the flow of curtain gas.