A system and method is provided for characterizing earth formations. A stent is placed concentrically around the flexible outer member, near the distal end of the catheter. The insert also preferably includes a blower or air pump for providing ventilation andor cooling to the seat occupant. The rotating component journal and the motor shaft are connected by the coupling in a manner that allows for the absorption of tensile and pressure stress. The mixing chamber length is designed so that the gas and the liquid droplets approach thermal equilibrium as the gas-liquid mixture moves into a separation chamber.