Turbo/drag pump having a composite skirt

A turbo/drag vacuum pump comprising a rotor having an upstream rotor segment of a turbine type and a downstream rotor segment in the form of a Holweck type skirt, the upstream rotor segment being made of metal or alloy, the downstream rotor segment being made of organic matrix composite material, and the downstream rotor segment being connected to the upstream rotor segment via an annular connection region,

• wherein:
• the downstream rotor segment comprising a Holweck type skirt made of organic matrix composite material has a fiber reinforcing structure imparting mechanical characteristics to the Holweck skirt that vary as a function of the longitudinal region under consideration of the skirt,
• in the annular connection region, the organic matrix composite material presents mechanical and thermal characteristics close to those of the metal or alloy constituting the upstream rotor segment, and
• in the downstream region of the skirt, the organic matrix composite material presents characteristics that are more suitable for withstanding the high mechanical stresses that result in this downstream region of the skirt from the high-speed rotation of the rotor in operation.