Downhole turbine

A downhole assembly, comprising:

• a downhole tool string component comprising a bore adapted to accommodate drilling mud;
• a fluid barrier disposed within the bore and comprising a cylindrical portion substantially aligned with the bore;
• a drive shaft sealed within and substantially coaxial with the cylindrical portion and comprising a first magnet disposed on its outer surface;
• a turbine assembly disposed around the cylindrical portion of the fluid barrier comprising an inner diameter and outer surface;
• the outer surface of the turbine assembly comprises a plurality of turbine blades;
• the inner diameter of the turbine assembly comprising a second magnet disposed within a region defined by the turbine blades and being in magnetic communication with the first magnet of the drive shaft;
• wherein when the drilling mud engages the turbine blades the first and second magnets rotate the drive shaft with the turbine assembly and wherein the drive shaft is in communication with at least one gear box disposed within the fluid barrier.