A heater assembly includes a continuous series of perforated helical members and a plurality of heating elements. The perforated helical members cooperate to define a geometric helicoid disposed about a longitudinal axis of the heater assembly. Each perforated helical member defines opposed edges and a predetermined pattern of perforations. The perforations extend through each perforated helical member parallel to the longitudinal axis. The heating elements extend through the perforations.