As the working power of Hall thrusters increases, the overall temperature of the thrusters will rise accordingly. A significant increase in temperature can lead to a decline in work performance and structural failure of the thruster. Therefore, a reasonable thermal design can significantly enhance the performance stability and reliability of Hall thrusters.

The purpose of this paper is to provide engineering guidance for the reasonable thermal design of a 12.5 kW Hall thruster without a cooling plate. In addition, a thermal model of the thruster is established and verified for the continuous optimization of the thruster’s structure.

The heat loss distribution of the 12.5 kW Hall thruster is calculated by theoretical analysis, then FEM (finite element method) is used to bulid the thermal build of a 12.5 kW Hall thruster, and six different thermal design methods are proposed in this paper. In addition, the effectiveness of different thermal design methods is analyzed by finite element simulation combined with a thermal balance experiment.

The results show that the average temperature rise of each thruster part reaches 50~150 ℃ after the cooling plate is removed. Therefore, considering the main heat transfer paths of the thruster, six thermal design methods are proposed and simulated, respectively. The results indicate that Method 4 and Method 6, namely, intercept the radiation heat exchange between the hollow cathode and the inner coil, and increasing the emission coefficient of outer magnetic screen and the outer coil sleeve. Meanwhile, based on Method 1, that is, blocking the heat conduction between the inner coil and the magnetic base, then a 5-mm-thick heat insulation pad is added between the inner coil and the magnetic base. The test results show that the comparison errors between simulations and the measurements of each component are less than 10%, and the comparison error between the magnetic base and the thruster base is the largest, which is caused by the top-down axial heat conduction in the test.

Axial heat conduction and radial heat radiation are the main heat transfer methods of the Hall thruster. According to the research results, the combination of Method 4 and 6 is the most effective way for thermal design optimization. Subsequently, the process will be verified to achieve the purpose of significantly reducing the temperature of the thruster.