nozzle for thermal spray gun , thermal spray gun and method of optimizing nozzle of thermal spray gun . the nozzle includes a central bore comprising a conical bore and a cylindrical bore . the conical bore is delimited by a conical wall surface in a conical bore section , the cylindrical bore is delimited by a cylindrical wall surface in a cylindrical bore section , and the conical bore section and the cylindrical bore section are structured so that heat is removed more rapidly from the conical wall than from the cylindrical wall .