Question

An engineer proposes to store 70 kJ of energy by flowing 1.6 kA of current through a superconducting solenoid that forms an inductor. (a) What is the required inductance L? (b) If the solenoid is to have a radius of 1.2 m and be wound with no more than 7 turns per meter, what length must the solenoid have?

Answer 1

a) E = 0.5LI^2

70000 = 0.5*L*1600^2

L = 0.0546 H = 54.6 mH

b) L = uN^2 A/ l

0.0546 = 4pi*10^-7*7^2 *pi*1.2^2 / l

l = 0.005 m = 5 mm