Atomizer and electronic cigarette

An atomizer, comprising:

• an external sleeve defining an air intake hole;
• and
• a heating assembly received in the external sleeve,
• wherein the heating assembly comprises:
• a tobacco holder defining an atomizing chamber for filling fuming material, the tobacco holder defining a ventilation hole which fluidly communicates with the atomizing chamber, and
• a heating member for heating the tobacco holder;
• wherein a spiral-shaped air intake passage is formed outside the tobacco holder and wound around the tobacco holder, both the air intake hole and the ventilation hole fluidly communicate with the air intake passage, the tobacco holder and/or the heating member configured to heat the air intake passage,
• wherein the heating assembly further comprises an internal sleeve sleeved over the tobacco holder, the internal sleeve is provided with a helical flange on an external peripheral surface thereof, and a side of the helical flange away from the external peripheral surface of the internal sleeve resists an internal peripheral surface of the external sleeve, or the external sleeve is provided with a helical flange on an internal peripheral surface thereof, and a side of the helical flange away from the internal peripheral surface of the external sleeve resists the external peripheral surface of the internal sleeve, the air intake passage is constituted by a space formed by the helical flange, the internal peripheral surface of the external sleeve, and the external peripheral surface of the internal sleeve,
• wherein a lower end of the external peripheral surface of the internal sleeve defines an air intake cutout, the air intake passage extends to the lower end of the internal sleeve, and the air intake passage is in fluid communication with an internal chamber of the internal sleeve via the air intake cutout, and
• wherein the tobacco holder comprises an atomizing tube and forms an end cover at an end of the atomizing tube, the end cover forms external threads at an external peripheral surface thereof, the external sleeve comprises a tubular circumferential wall, the tubular circumferential wall forms an external peripheral flange extending outwardly at an upper end of the tubular circumferential wall, the external peripheral flange is adjacent to a terminal of the upper end of the tubular circumferential wall, an annular section is formed between the terminal of the upper end of the tubular circumferential wall and the external peripheral flange, the annular section defines at least one air intake hole at a circumferential wall of the annular section, an internal peripheral surface of the annular section forms internal threads engaging with the external threads on a periphery of the end cover.