Basic constructions and different types of insulation materials used in HVDC cables

Hi, For this paper, please introduce the basic constructions and different types of insulation materials used in HVDC cables. About different types, we have found 2 types they are mass-impregnated cables and extruded insulation cables. So you only need to write about these two types. Please find some graphs and add to the paper which can help to get a higher mark. IEEE citation is required.