采用平行平板结构的微间隙介质阻挡放电装置，在锯齿波电压激励下产生了电流波形具有平台状的阶梯模式放电。研究发现，随锯齿波电压峰值的增大，放电平台的持续时间和幅值随之增加。采用光学方法对单个放电平台的时间演化进行研究，发现其放电机制属于大气压汤森放电。通过对放电的发射光谱进行采集，发现包含氮分子的第二正带系(C3Πu→B3Πu)、OH(A2∑+→X2Π)和ArⅠ的特征谱线。随锯齿波电压峰值的增大，OH(308.8 nm)谱线强度和分子振动温度增加，但电子激发温度减小。通过对ArⅠ(750.4 nm)强度进行比较，发现相同峰值电压下锯齿波激励介质阻挡放电比正弦激励介质阻挡放电产生的谱线强度更大。利用气体放电理论，对上述物理现象进行了定性解释。

A micro-gap dielectric barrier discharge decive in a parallel plate geometry is excited by a saw-tooth voltage to produce a stepped discharge, whose current waveform presents a plateau every half voltage cycle. It is found that the duration and amplitude of the discharge plateau increase with the increasing of the peak value of the applied saw-tooth voltage. The temporal evolution in the discharge plateau is investigated through optical method. It is confirmed that the stepped discharge is in an atmospheric Townsend discharge regime. Scanning the optical emission spectrum from the discharge, it is found that the spectrum is composed of the second positive system of nitrogen molecule(C3Πu→B3Πu), OH(A2∑+→X2Π) and Ar Ⅰ. With the increasing of the peak value of the applied saw-tooth voltage, it increases for the spectral intensity of OH (308.8 nm) and the molecular vibrational temperature, while the excited electron temperature decreases. By comparing the spectral line intensity of Ar Ⅰ(750.4 nm), it is found that the spectral line intensity produced by saw-tooth wave excited dielectric barrier discharge is larger than that of sine wave excited dielectric barrier discharge under the same peak voltage. All of these physical phenomena mentioned above are analyzed qualitatively by gas discharge mechanism.