A gridded ion thruster ionizes propellant and electrostatically accelerates the resulting positive ions out the back to produce thrust. Because every expelled ion carries away positive charge, the spacecraft itself would otherwise build up an increasingly negative net charge — which then electrostatically pulls the beam back toward the spacecraft, cutting thrust, and risks electrostatic discharge into onboard electronics. This simulator lets you run the thruster with an adjustable ion-expulsion rate and a separate neutralizer electron-emission rate, watching the spacecraft's net charge, the beam's trajectory and the effective thrust respond in real time as you balance — or fail to balance — the two.