中文摘要：

Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges(DBDs) in atmospheric-pressure helium was carried out to study the discharge mechanism.Using an intensified charge-coupled device(ICCD) and a grating spectrometer,we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs.We also studied the time variation of typical emissions from He,O and first negative bands of N+ 2.The results showed that the spectral lines do not develop synchronously as N+ 2(B2u+X2∑+g,0~0,λ=391.4 nm) and N∑+2(B2∑+u → X2∑+g,0~1,λ=427.8 nm) appear earlier and last for a longer time than He(33S1 → 23P1,λ=706.5 nm) and O(35P→35S,λ=777.4 nm).A certain number of He metastables produced in the initial stage of discharge.Even between adjacent pulses,the emissions from N∑+2 can still keep certain intensities while those from He and O extinguish.Since long-lifetime He metastables are produced and exist in the discharging space,it is the Penning ionization that keeps the long decay of N∑+2 emissions.

英文摘要：

Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges （DBDs） in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device （ICCD） and a grating spectrometer, we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs. We also studied the time variation of typical emissions from He, 0 and first negative bands of N＋_2. The results showedthat the spectral lines do not develop synchronously as-N_2（B_2∑U＋x2∑＋G,0～0,λ=391.4nm）and N＋2（B2∑＋u→X2∑＋g,0～1,λ=427.8nm） appear earlier and last for a longer time than He（3_3S1→2_3P1,λ=706.5nm）and O （3_P→3_5S,λ=777.4nm） A certain number of He metastables produced in the initial stage of discharge. Even between adjacent pulses, the emissions from N＋2 can still keep certain intensities while those from He and 0 extinguish. Since long-lifetime Hemetastables are produced and exist in the discharging space, it is the Penning ionization thatkeeps the long decay of N＋ emissions.