Electrical connection to Fig.2.2 is made such that positive terminal is
in contact with the stagnation point while negative terminal is
contacting the shoulder ends. This will allow electric current to flow
through the entire heat shield from stagnation point to shoulder ends.
Hence, the current spreads out like an umbrella with highest energy
density at the centre and lowest energy density at the shoulder ends.
Length of heat shield is approximately equal to length of arc.
\(Length=\frac{\theta}{360}X\ 2\Pi r\left(\deg rees\right)=\frac{\theta}{2\Pi}X2\Pi r=r\theta\ \ Eq\ 2.1\)
Cutting a 90\(^o\) \(\left(\frac{\Pi}{2}\right)\) sector from a sphere of
100mm diameter gives a heat shield length of 50\(\Pi\)mm. Connecting a
cylindrical tungsten rod of 10mm diameter to the graphite heat shield
gives a simulation result in Fig.2.3.