To provide a method of obtaining coherent gas jet and an apparatus useable for obtaining the coherent gas jet.

There is provided a method of forming a coherent gas jet comprising: supplying main gas to a nozzle to form a main gas jet having a central axis by permitting the main gas to go out from the nozzle, and surrounding the main gas jet with a flame envelope, and further directing the flame envelope in the direction of the central shaft of the main gas jet. There is further provided an apparatus for forming a coherent gas jet comprising: a main gas nozzle capable of injecting the main gas with a high speed to form a main gas jet having a central axis, means for forming a flame envelope around the main gas jet, and means for directing the flame envelope to the main gas jet.