Abstract:
A method includes creating a gas flow in a gas cell and cooling a portion of the gas flow to create a thermally-induced temperature gradient in the gas flow. The method also includes directing at least one laser beam through at least a portion of the gas flow with the thermally-induced temperature gradient. The gas flow can be directed axially along a length of the gas cell or transverse to the length of the gas cell, and the at least one laser beam can be directed axially along the length of the gas cell through at least the portion of the gas flow. The gas flow may represent a first gas flow, and the method may further include creating a second gas flow in the gas cell and cooling a portion of the second gas flow to create a thermally-induced temperature gradient in the second gas flow.