**2. Impulse measuring principle**

The basic principle behind most existing measurement methods is to apply the thrust or impulse to be measured on the measuring platform, establish the functional relationship between the thrust and impulse, and the corresponding physical effect according to the mechanical response results of the measuring platform (e.g., vibration amplitude and rotation angle), and then calibrate the functional relationship through the standard force, thereby achieving the quantitative measurement of thrust and impulse. In electric thrusters, the key to micro-thrust and impulse measurement is to measure the variation of thrust with time. For thrusters operating in a transient state (e.g., pulsed plasma thrusters), the thrust action time is very short, and it is unnecessary or impossible to measure the variation of thrust with time. In this case, the thrust action effect can be expressed by impulse, which is also the impulse measurement [11–13].
