A dilution refrigerator with large cooling power

A dilution refrigerator with sintered copper heat exchangers and a He³ circulation rate of 1.4 × 10⁻⁴ − 3 × 10⁻⁴ mole s⁻¹ is described. The cooling power at 15 mK is 1μW. Construction of the cryostat and the pumping system is discussed in detail. Heat transfer in the exchangers and in the mixing chamber is discussed and measurements of thermal contact between the mixing chamber and an outside load are presented.