for use in combination with a heat engine , a thermal energy transformer comprising a flux receiver having a first wall defining therein a radiation absorption cavity for converting solar flux to thermal energy characterized by a first wall defining a radiation absorption cavity having a solar flux entry aperture , and a second wall defining an energy transfer wall for the heat engine , and a heat pipe chamber interposed between the first and second walls having a working fluid disposed within the chamber and a wick lining the chamber for conducting the working fluid from the second wall to the first wall , whereby thermal energy is transferred from the radiation absorption cavity to the heat engine .