The electric field in the He:N₂ nanosecond atmospheric pressure plasma jet is studied using the electric-field induced second harmonic generation technique. It is shown that the calibration obtained with a DC voltage applied to the discharge cell may lead to incorrect results in the electric field measurements. It is proposed to use nanosecond high voltage pulses at low repetition rates for the calibration instead of a DC voltage. The temporal development of the electric field in the discharge at different distances from the cathode is measured with high temporal (100 ps) and spatial (50 m) resolution. An electric field profile structure similar to the one in streamers or ionization fronts is observed. The velocity of the propagation of the falling edge of the ionization front is determined to be 0.85 10⁶ m s⁻¹. The validity of the local field approximation, important for modeling of these kind of discharges, is confirmed for the present conditions based on time and space derivatives of the measured electric field. The temporal evolution of the electron density is obtained by the measured electrical current and the time resolved electric field measurement combined with the electron mobility calculated with BOLSIG+.

使用电场感应的二次谐波产生技术研究了He：N ₂纳秒大气压等离子体射流中的电场。结果表明，使用直流电压施加到放电室获得的校准可能会导致电场测量结果不正确。建议使用低重复频率的纳秒级高压脉冲代替直流电压。在高时间（100 ps）和空间（50 ps）下测量离阴极不同距离处放电中电场的时间发展m）分辨率。观察到类似于在流光或电离前沿中的电场分布结构。电离前沿的下降沿的传播速度被确定为0.85 10 ⁶ ms ^-1。对于当前条件，基于所测量电场的时间和空间导数，证实了局部场近似的有效性（对于建模此类放电很重要）。电子密度的时间演变是通过测得的电流和时间分辨电场测量值结合BOLSIG +计算出的电子迁移率获得的。