Apparatus and method for supplying sealing air to an exhaust turbine that interacts with an internal combustion engine for turbo-compound operation in a vehicle. The N material may be of large area, crack-free character, having a defect density as low as 3\xd7106 defectscm2 or lower. By impressing an alternating current between the first electrode and the second electrode, non-equilibrium plasma discharge between the insulating member and one of the first electrode and the second electrode is promoted. The rotational coupling interconnects the heating element with the housing.