Arc motion and splitting of vacuum arc at intermediate frequency（400-800 Hz） were investigated under transverse magnetic field（TMF）.The experiment was performed on cup-type TMF contacts with contact diameter of 40 mm and a contact gap of 4 mm in a single-frequency circuit.With high-speed photography we characterized the arc appearance at different arc currents from 3.3 kA-rms to 10 kA-rms at intermediate frequencies.As arc current increases from3.3 kA-rms to 10 kA-rms the arc appearance changes obviously.When current value is 3.3 kArms（current frequency 400-800 Hz）,there is almost no splitting arc;when the current exceeds5 kA-rms（current frequency 400-800 Hz）,the arc rotates at a speed above 20 m/s,accompanied by an observable splitting arc.The splitting arc could be observed at different frequencies and the arc-voltage had no noises when splitting occurred.The motion direction and the velocity of arc column were studied.Finally,the formation of a split arc was discussed.
目前应用于未来多电和全电飞机（电流频率360～800Hz）的中频真空开关正成为研究热点，中频真空电弧理论的研究正不断深入。分析了电弧等离子体连续光谱的辐射理论，在假定中频真空电弧处于部分局部热力学平衡态（partial local thermodynamic equilibrium，PLTE）的基础上，结合实际光学通路的简化模型，得到通过双波段窄带连续光谱测量电子温度和电子密度的方法，然后设计了中频真空电弧的参数测量系统实现上述过程。该系统由添加了双波段窄带滤光片的彩色数字电荷耦合器（change．coupleddevice，CCD）摄像机和电弧图像数据分析程序组成，能够同时拍摄电弧图像并获取所需数据。在对光学通路模型进行标定后，利用该系统观测了中频（400、650和800H而电弧形态的演变，并测量了真空电弧的电子温度和电子密度，结果表明理论分析和实验过程有效。中频情况下，电弧主要呈现过渡态电弧和扩散态电弧2种形态。过渡态电弧演变迅速，并在电流峰值时刻转变为扩散态电弧。有效值约为8kA的中频电流在峰值时刻电子温度处于0．5～3eV之间，而电子密度量级为10^20-10^21 m^-3，这些与其他学者得到的电弧等离子体参数相符。
