Abstract: In a preferred embodiment, a non-linear thermal coupling to connect a heat load to a powered cooler, the coupling including: first and second thermal transfer elements, the first transfer thermal transfer element being thermally connected to the heat load and the second thermal transfer element being thermally connected to the powered cooler; the first and second thermal transfer elements being physically separated by a first gap when the first and second thermal transfer elements are at a relatively high temperature, and the first and second thermal transfer elements being in mutual physical contact when the first and second thermal transfer elements are at a relatively low temperature so as to thermally connect the heat load and the powered cooler; and the first and second thermal transfer elements being placed in the mutual physical contact by thermal contraction of a contracting element.