This paper presents the design and thermal analysis using COMSOL Multiphysics® of safety part of the extraction system of the heavy ion cyclotron DC280. The heavy ion cyclotron DC280 was developed and is being constructed at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research. High thermal power of the extracted beam is a risk of destruction for the elements of the beam extraction system. The beam power is expected to be about 2.5-3 kW and the beam diameter is about 10 mm. The proposed model analyses mainly the temperature on the exposed by the beam area of the windows, contact temperature between the windows made of molybdenum and the body made of cooper, and temperature on the wall of the cooling channel. The article also discusses possibility of design for experimental verification. The results based on thermal analysis will give us a possibility to choose an appropriate configuration for its experimental verification on the stand.