Question 5 (7 marks) A planar Langmuir probe, with a square collecting surface, has a side length of 5 mm and negligible thickness. It is found to have an electron saturation current of 20 {111% in a singly ionized argon plasma. The electron temperature is found to be 4 eV. (a) Calculate the approximate plasma density. (Note: the probe collects current from both sides.) [b] Calculate the Debye length. [c] Assuming this is a one-dimensional problem because the Debye length is much smaller than the dimensions of the probe, how would you obtain the isotropic velocity distribution function u] from the current versus voltage curve obtained from the probe? You do not have to carry out a full derivation but do need to describe the mathematical operation/s that need to be carried out