Abstract: A cooling system for use with a gas turbine combustion assembly having a flame tube and a surrounding air delivery sleeve, the system comprising a vessel shaped and dimensioned to surround the air delivery sleeve and adapted for fluid flow there through. A method of cooling a combustion assembly includes the step of directing a flow of fluid over an outer surface of the delivery sleeve.

Abstract: Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.