**3.1 The magnetic system of Brown**

The system of Brown is a rotating system and employs an Ericsson cycle (Yu, 2003). The magnetic field is produced by an electromagnet (water cooled) with a maximum magnetic field of 7 T. The MCE material used is the Gd in the form of plates with 1 mm thickness, separated by stainless steel wires with 1 mm intervals to allow the regenerator fluid to flow vertically. The fluid is composed of 80% of water and 20% of alcohol. Without load and after 50 cycles, the temperatures reached were 46 ° C for the heat source and -1 ° C for the cold source, thus 47 C Δ= ° *T* . However, the cooling power obtained was not rely important, this is due to the large Δ*T* obtained. Moreover, the cycle can operate only at low frequencies; the temperature gradient is reduced because both warm and cold sides have time to interact.
