Design of a Current Measurement System in a Plasma Thruster with Rogowski Coil

The development of plasma thrusters for microsatellites is mostly based in intensive testing, so the implementation of measurement devices for characterizing their real response is required. One of the most significant parameters is the current flowing through the plasma at the time of ignition; its quantification requires an instrument capable of measuring current peaks between -14 kA and +10 kA, without interrupting the circuit that produces it. That´s why a Rogowski coil has been chosen as the ideal measurement method. When the coil is mounted around the conductor carrying the current to be measured, it produces a voltage proportional to its derivate. Using an operational amplifier, adapted to the discharge current frequency of the plasma generating circuit, an active integration of the Rogowski coil output signal is performed. The work begins by defining the Rogowski Coil characteristic parameters and the integrator circuit which converts its output to a signal proportional to the measured current. Subsequently, the related hardware is implemented and functional tests are performed.