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AbstractThe pulsed washer gun–generated plasma released into an evacuated chamber has been diagnosed using the spectroscopic technique. By analyzing the recorded spectral lines of argon plasma, the electron temperature is determined using the spectral line ratios of the Ar ion and Ar atom following the Corona model. The light is collected using an optical fiber placed at a glass port of the chamber and fed into a digital spectrometer to obtain the emitted spectra from plasma in front of the plasma gun mouth. As the plasma diffuses after ejecting out into the evacuated chamber from the plasma gun, the Corona model is an appropriate model for the electron temperature estimation. Large differences in estimated electron temperatures are observed when the Boltzmann plot method, assuming the local thermal equilibrium model for the atomic and ionic lines separately, is used. To study the effect of base pressure in the evacuated chamber on the electron temperature of the plasma ejecting out of the gun, the electron temperature with different base pressures ranging from 20 to 100 Pa is measured and analyzed.