2kW射频板条CO2激光器射频频率漂移特性研究

Research of effect of frequency fluctuation on the performance of a 2kW RF-excited slab CO_2 laser

为了研究射频板条CO2激光器射频频率波动对输出光束的影响,采用等效电路分析和实验测量的方法研究了射频频率对激光器输入输出特性的影响。计算得到射频频率变化2MHz时引起的阻抗实部变化率为0.01%,说明射频频率漂移对放电部分等效电路参量影响很小。射频频率采用79.4MHz,80.0MHz,80.7MHz,81.4MHz,82.0MHz和82.7MHz,以设计频率81.4MHz对应的输出功率为基准,占空比设置为80%时,频率漂移1MHz则激光功率下降约150W。激光功率随频率变化趋势与理论结果一致。结果表明,射频频率变化引起的阻抗匹配问题是导致输出功率波动的主要原因,可以通过改进匹配网络来克服射频频率的波动对激光器性能的影响。

In order to investigate influence of electronic tube radio frequency(RF) power frequency fluctuation of 2kW RF slab CO2 laser on output beam, the influences of RF frequency on laser input and output characteristics were analyzed through equivalent circuit analysis and experiment measurement. When frequency offset was 2MHz, real component of load impedance had the change of 0. 01%. RF frequency drift had little effect on equivalent circuit parameters of discharge portion. When using the radio frequency of 79. 4MHz, 80. 0MHz, 80. 7MHz, 81. 4MHz, 82. 0MHz and 82. 7MHz, with corresponding output power of 81. 4MHz design frequency set as benchmark, with the duty cycle set as 80%, laser power decreased about 150W with frequency drift of 1MHz. The computational results were consistent with the experimental results well. The results show thatthe impedance matching problem caused by frequency fluctuation is a major factor that deteriorates the RF slab laser performance. This problem can be solved by improving the matching network.