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.