Abstract: For optimizing the structure of plasma jet igniter and improving its performance，the effect of an. ode channel length，including discharge characteristic，spectrum characteristic，jet characteristic and ignition characteristic，were studied experimentally on the basis of the self-designed plasma ignition experimental sys.tem. The selected anode channel length is 3mm，5mm and 7mm. The results indicate that with the increasing ofthe anode channel length the magnitude of the arc shunting is suppressed，the ablation area of the electrode is re. duced，but the elongation of anode channel will lead to breakdown voltage increase，and the arc ignition process will be more difficult. With the increasing of anode channel length，rotational temperature of nitrogen molecular ions is rising firstly and then decreasing，while vibrational temperature shows the opposite trend. And the ignitiondelay time of kerosene/air mixture shows the trend of decreasing firstly and then increasing. When excess air coef.ficient is 1.43，the ignition delay time of 5mm anode channel length is 14.4ms. Compared with the 3mm and 7mmanode channel length，the ignition delay time is reduced by 21.1% and 12.1%，respectively.

Key words: Plasma jet ignition；Anode channel length；Discharge characteristic；Spectrum characteris. tic；Ignition delay

摘要： 为进一步优化等离子体射流点火器的结构，提高点火器的工作性能，在自主设计的等离子体点火实验系统的基础上，开展了阳极通道长度对等离子体射流点火器特性影响的实验研究，选取的阳极通道长度为 3mm，5mm和 7mm。获得了等离子体射流点火器的放电特性、光谱特性、射流特性和点火特性。结果表明:增大阳极通道长度能够抑制电弧分流的幅度，减小电极的烧蚀面积，但提高了击穿电压，使引弧更加困难；随着阳极通道长度的增大，氮分子离子的转动温度和振动温度分别呈现出先升高后降低和先降低后升高的变化趋势；煤油 /空气混合气的点火延迟时间随阳极通道长度的增加，呈现出先减小后增大的变化趋势，余气系数为 1.43时，阳极通道长度 5mm时的点火延迟时间为 14.4ms，相对于阳极通道长度 3mm，7mm下的点火延迟时间分别减小了 21.1%，12.1%。

关键词: 等离子体射流点火；阳极通道长度；放电特性；光谱特性；点火延迟