This invention concerns a compact fluorescent lamp with a double helix shaped discharge tube in which the two strands of the helix are constituted by two helix shaped tube portions. These tube portions define a central axis of the discharge tube. The double helix formed by the discharge tube has a central section and a first end section. These sections are defined along the central axis, and the lamp base for receiving ends of the tube portions is disposed at the first end section. An inner diameter of the central section of the helix is larger than an inner diameter of the first end section. The invention further relates to a method and apparatus for manufacturing coiled shaped discharge tubes, in particular the above described discharge tube of the discharge lamp. A radially segmented molding core is used for manufacturing the discharge tube. Once the coiling of the discharge tube on the molding core is completed, the segmented molding core is shrunk radially, and then is withdrawn from the coiled discharge tube axially.