Abstract: This invention relates to a cooling apparatus comprising a base plate, an evaporator and a condenser. In order to obtain a simple and efficient cooling apparatus the evaporator is a porous aluminum evaporator having a capillary structure with pores and a plurality of larger sized evaporator channels extending through the evaporator between a second end and the first end of the evaporator. A compensation chamber extending along a second surface of the evaporator receives first fluid from the condenser such that pores opening up into the second surface of the evaporator are provided with first fluid.