Comparing Fig.2.7 with Fig.2.5, one can easily spot out the effect of different electrical conductivities (graphite and tungsten). Current flows through tungsten up to midway of the heat shield before actually flowing through the heat shield material. The part of the heat shield in contact with tungsten is cold because it is easier for current (which produces Joule heating) to flow through tungsten and not graphite. On the other hand tungsten has a lower specific heat capacity \(\left(132JKg^{-1}K^{-1}\right)\) compared to graphite \(\left(710Kg^{-1}K^{_{-1}}\right)\). This implies that heat holding capacity of graphite is 5.4 times higher than that of tungsten. Again compared to graphite, tungsten has higher thermal conductivity making it act as a heat sink. Hence Fig.2.5 and 2.7 are not desirable and not what is intended to be achieved. Hence further improvement through prototype optimisation will result in better hypersonic re-entry temperature fields.