A method of producing a radiating plasma with an increased flux stability and uniformity is disclosed. The method comprises the steps of generating a primary target by urging a liquid under pressure through a nozzle; directing an energy pre-pulse onto the primary target to generate a secondary target in the form of a gas or plasma cloud; allowing the thus formed secondary target to expand for a predetermined period of time; and directing a main energy pulse onto the secondary target when the predetermined period of time has elapsed in order to produce a plasma radiating X-ray or EUV radiation. The pre-pulse has a beam waist size that is larger, in at least one dimension, than the corresponding dimension of the primary target.

A method and an arrangement for generating x-ray or EUV radiation are disclosed. Target material is supplied from a container for target material to a jet-forming orifice in an interaction chamber by means of a flexible capillary tubing of considerable length, wherein the orifice is an integral part of the capillary tubing. A jet formed by urging target material through the orifice is made to interact with a beam of energy, thus producing a radiating plasma emitting the desired electromagnetic radiation. The use of a flexible capillary tubing for supplying target material from a source of target material to an orifice, which is integrated with the tubing, within an interaction chamber, in order to form therein a jet of target material for interaction with an energy beam to generate x-ray or EUV radiation, is also disclosed.

In a method of generating X-ray or EUV radiation, a substance is urged through an outlet to generate a jet in a direction from the outlet, at least one energy beam is directed onto the jet, the energy beam interacting with the jet to generate the X-ray or EUV radiation, and the temperature of the outlet is controlled, such that the stability of the jet is improved. An apparatus is also disclosed.