A cooling system , comprising: a heat conductive body heated by a heat source , the heat conductive body having an external surface configured for being exposed to a low-pressure environment; a tank containing an evaporation liquid having a pressure greater than a pressure of an environment near the external surface; a conduit being in hydraulic communication with the tank and configured to supply the evaporation liquid to the external surface of the body; a controllable supply valve arranged within the conduit, and configured for regulating a flow rate of egress of the evaporation liquid from the tank; and a control unit operatively coupled to said controllable supply valve, and configured for controlling operation thereof for supply of the evaporation liquid, the control unit comprising: a temperature sensor arranged within the body at a predetermined place and configured for producing a temperature sensor signal representative of the temperature of the body at the predetermined place; and a controller operatively coupled to said temperature sensor and to said controllable supply valve , said controller being responsive to said temperature sensor signal and being capable of generating control signals for controlling operation of said controllable supply valve by turning it "on" or "off", thereby to provide a pulsed supply of the evaporation liquid to the external surface of the body as long as required for obtaining a desired temperature decrease of the body at the predetermined place; the system characterized in that the controller is configured to control operation of the controllable supply valve , so as_to release a volume of the evaporation liquid in the amount of between 80% and 100% of an inner volume of the conduit between the controllable supply valve and an outlet orifice(s) . a heat conductive body heated by a heat source , the heat conductive body having an external surface configured for being exposed to a low-pressure environment; a tank containing an evaporation liquid having a pressure greater than a pressure of an environment near the external surface; a conduit being in hydraulic communication with the tank and configured to supply the evaporation liquid to the external surface of the body; a controllable supply valve arranged within the conduit, and configured for regulating a flow rate of egress of the evaporation liquid from the tank; and a control unit operatively coupled to said controllable supply valve, and configured for controlling operation thereof for supply of the evaporation liquid, the control unit comprising: a temperature sensor arranged within the body at a predetermined place and configured for producing a temperature sensor signal representative of the temperature of the body at the predetermined place; and a controller operatively coupled to said temperature sensor a temperature sensor arranged within the body at a predetermined place and configured for producing a temperature sensor signal representative of the temperature of the body at the predetermined place; and a controller operatively coupled to said temperature sensor and to said controllable supply valve , said controller being responsive to said temperature sensor signal and being capable of generating control signals for controlling operation of said controllable supply valve by turning it "on" or "off", thereby to provide a pulsed supply of the evaporation liquid to the external surface of the body as long as required for obtaining a desired temperature decrease of the body at the predetermined place; the system characterized in that the controller is configured to control operation of the controllable supply valve , so as_to release a volume of the evaporation liquid in the amount of between 80% and 100% of an inner volume of the conduit between the controllable supply valve and an outlet orifice(s) . <EOS>