Study on the laser collisional induced fluorescence spectrum of helium plasmas

Highlights: • Laser induced fluorescence and laser collisional induced fluorescence spectra of helium plasma were measured. • Peak heights of spectral lines for the 33S-23P, 33P-23S transitions were decreased despite of the laser irradiation. • The behaviors of laser collisional induced fluorescence spectra were discussed using helium collisional-radiative model. Helium (He) RF plasma source was configured to study laser collisional induced fluorescence (LCIF) spectrum of He plasma. When laser beam with wavelength of 396.5 nm resonant to the $2^{1}S-4^{1}P$ transition line was incident on He plasmas LCIF spectral lines of singlet state transitions as well as triplet state transitions were measured. The peak heights of spectral lines for the $3^{3}S-2^{3}P$, $3^{3}P-2^{3}S$, and $3^{1}P-2^{1}S$ transitions decreased despite of laser irradiation. The change in He LCIF spectra by the singlet-to-triplet transition were discussed using collisional-radiative model for LCIF process.