2, [20 pts] Answer the following questions: A. Explain the nature of the electrostatic eld shielding inside a plasma volume in absence of magnetic field. What is characteristic depth of the electrostatic field penetration into the plasma volume? B. How and Why this constraint can be removed by applying a constant magnetic eld to the plasma volume? How is this concept implemented in Hall thrusters? C. Hall thruster can he called an electrostatic device relieved from the spacecharge limitation. Explain why