A method of electron density measurement inside discharge channel of pulsed-plasma thruster(PPT) with higher accuracy was proposed,based on Stark broadening spectrum analysis.By measuring the line profile and the full-width at half-maximum(FWHM) of C atom spectrum emitted by PPT plasma,the electron density can be calculated.But this requires adequate high electron density.If the electron density is lower than 10~(16) cm~(-3),the accuracy of diagnosis is dramatically decreased.Therefore,a tiny H tracer based...