Systems, assemblies and methods for thermally managing a grazing incidence collector (GIC) for EUV lithography applications are disclosed. The GIC thermal management assembly includes a GIC mirror shell interfaced with a jacket to form a sealed chamber. An open cell, heat transfer (OCHT) material is disposed within the metal chamber and is thermally and mechanically bonded with the GIC mirror shell and jacket. A coolant is flowed in an azimuthally symmetric fashion through the OCHT material between input and output plenums to effectuate cooling when the GIC thermal management assembly is used in a GIC mirror system configured to receive and form collected EUV radiation from an EUV radiation source.