真空断路器电弧等离子体径向分布与粒子扩散过程的发射光谱诊断

Emission Spectrum Diagnosis on Radial Distribution and Particle Diffusion Process of Vacuum Arc Plasma

真空断路器中,与工频相比,中频真空电弧由于燃弧时间短、电流变化率较大等原因更容易发生弧后重击穿现象,导致开断容量不足,获取开断过程中的微观粒子参数信息有助于提高真空断路器的开断容量。对此,借助发射光谱法对真空电弧内的等离子体参数进行诊断,研究在不同电流频率(570 Hz、735 Hz、1020 Hz)与电流幅值(2~5 kA)条件下电子密度的径向分布规律,结合获取到的铜原子谱线对燃弧过程中铜原子的扩散过程进行分析。得到电子密度的径向分布呈现中心区域高、边缘区域低的类高斯分布,相同电流幅值下,电子密度随着频率的升高而升高。735 Hz频率条件下,电流峰值时刻的电子密度峰值由2 kA电流峰值下的9.36×10^(17) m^(-3)上升为5 kA电流峰值下的3.65×10^(21) m^(-3)。随着电流幅值的上升,铜原子的扩散速度由逐渐上升转化为逐渐下降,其径向扩散速度在数米每秒至80 m/s的范围内变化,不同电流幅值下电子的径向扩散速度逐渐下降,其径向分布范围大于铜原子的范围。

In the vacuum circuit breaker,compared with the power frequency,the intermediate frequency vacuum arc is easier to be re-stroken after arcing due to short arc burning time,high current changing rate and other reasons,which leads to insufficient breaking capacity.It is helpful to improve the breaking capacity of vacuum circuit breaker to obtain the parameter information of micro particles in the breaking process.Therefore,by using the emission spectrum method,this paper diagnoses plasma parameters in the vacuum arc,and studies radial distribution of the electron density under different current frequencies(570 Hz,735 Hz,1020 Hz)and current amplitudes(2~5 kA).It also analyzes the diffusion process of copper atoms in arc burning process by combining the obtained copper atomic spectrum lines.The results show that the radial distribution of electron density presents a Gaussian distribution with high central region and low edge region.Under the same current amplitude,the electron density increases with the increase of frequency.I n the case of 735 Hz frequency,the electron density peak value increases from 9.36×10^(17) m^(-3) at the peak of 2 kA to 3.65×10^(21) m^(-3) at the peak of 5 kA at current peak time.With the increase of current amplitude,the diffusion velocity of copper atom changes from gradual increase to gradual decrease,and the radial diffusion velocity changes from a few meters to 80 m/s.Under different current amplitudes,the radial diffusion velocity of electrons decreases gradually,and the radial distribution range is larger than that of copper atom.