A permanently magnetized motor rotor 94 rotates within the motor can 82 of the mounting frame 70. A pump rotor 98 is mechanically and co-rotatably connected to the motor rotor 94 via a rotor shaft 102. The rotating pump rotor 98 pumps gas from the axial gas inlet port 30 to the tangential gas outlet port 34.

FIG. 3 shows an isometric view of the mounting frame 70 showing the inside of the stator bed 66 which embeds the magnet yoke 62 and the electro-magnetic coil 54 forming the motor stator 58. The stator bed 66 comprises a plane surface 106 surrounding the motor can 82 and being perpendicular to an axial direction of the motor can 82. The magnet yoke 62 is arranged on the plane surface 106 providing a large contact area with the plane surface 106 so that heat of the magnet yoke 62 is effectively conducted to the mounting frame 70. A heat conducting paste can be provided between plane surface 106 and the magnet yoke 62 in order to further improve the heat conduction between the magnet yoke 62 and the mounting frame 70.