A laser tool configured to operate within a wellbore of a hydrocarbon-bearing rock formation, the laser tool comprising: one or more optical transmission media, the one or more optical transmission media being part of an optical path originating at a laser generator configured to generate a laser beam having an axis, the one or more optical transmission media for passing the laser beam; an optical element that is part of the optical path, the optical element for receiving the laser beam from the one or more optical transmission media and for output to the hydrocarbon- bearing rock formation; and a purging head for removing dust or vapor from a path of the laser beam, the purging head for discharging two or more purging gas streams, characterized in that: the purging head comprises a helical flow assembly comprising: a helical gas inlet fitting in fluid communication with a gas conduit and a gas source for flowing a purging gas stream; a helical flow device body in fluid communication with the helical gas inlet fitting for receiving the purging gas stream from the helical gas inlet fitting, wherein the helical flow device body is connected to two diametrically opposed coaxial gas inlet fittings; a helical flow tip in fluid communication with the helical device flow body and comprising one or more holes or slots, that allow a fluid stream to pass through the helical flow tip, the helical flow tip for receiving the purging gas stream from helical flow device body and for discharging the purging gas stream in a helical pattern around and substantially along the axis; the helical flow tip being rotatable about the axis, wherein, in use, the rotation of the helical flow tip is caused by the purging gas stream passing through the one or more holes or slots. one or more optical transmission media, the one or more optical transmission media being part of an optical path originating at a laser generator configured to generate a laser beam having an axis, the one or more optical transmission media for passing the laser beam; an optical element that is part of the optical path, the optical element for receiving the laser beam from the one or more optical transmission media and for output to the hydrocarbon- bearing rock formation; and a purging head for removing dust or vapor from a path of the laser beam, the purging head for discharging two or more purging gas streams, characterized in that: the purging head comprises a helical flow assembly comprising: a helical gas inlet fitting in fluid communication with a gas conduit and a gas source for flowing a purging gas stream; a helical flow device body in fluid communication with the helical gas inlet fitting for receiving the purging gas stream from the helical gas inlet fitting, wherein the helical flow device body is connected to two diametrically opposed coaxial gas inlet fittings; a helical flow tip in fluid communication with the helical device flow body and comprising one or more holes or slots, that allow a fluid stream to pass through the helical flow tip, the helical flow tip for receiving the purging gas stream from helical flow device body and for discharging the purging gas stream in a helical pattern around and substantially along the axis; the helical flow tip being rotatable about the axis, wherein, in use, the rotation of the helical flow tip is caused by the purging gas stream passing through the one or more holes or slots. a helical gas inlet fitting in fluid communication with a gas conduit and a gas source for flowing a purging gas stream; a helical flow device body in fluid communication with the helical gas inlet fitting for receiving the purging gas stream from the helical gas inlet fitting, wherein the helical flow device body is connected to two diametrically opposed coaxial gas inlet fittings; a helical flow tip in fluid communication with the helical device flow body and comprising one or more holes or slots, that allow a fluid stream to pass through the helical flow tip, the helical flow tip for receiving the purging gas stream from helical flow device body and for discharging the purging gas stream in a helical pattern around and substantially along the axis; the helical flow tip being rotatable about the axis, wherein, in use, the rotation of the helical flow tip is caused by the purging gas stream passing through the one or more holes or slots.