Cutting gas nozzle and laser cutting method having a displaceable sleeve for setting the flow characteristics

A cutting gas nozzle for a laser machining head, the cutting gas nozzle comprising:

• an inner nozzle comprising a nozzle opening configured to form a core gas flow during processing;
• and
• an annular gap surrounding the nozzle opening and configured to form an annular gas flow that first flows through the annular gap and then exits the cutting gas nozzle in an annular exit flow between the inner nozzle and a sleeve in the annular gap during processing;
• wherein the sleeve is arranged to be axially displaceable between a rearward position and a forward position,
• wherein the sleeve projects beyond the inner nozzle at least when in the forward position, and wherein the sleeve opens a cross-sectional area of the annular gap to a variable degree as the sleeve is displaced from the rearward to the forward position.