pulse propagation velocity

例句：

1. 1.The speed of light in a vacuum is approximately 299,792 kilometers per second.
   光在真空中的速度大约是每秒299,792公里。
2. 2. The pulse propagation velocity of the laser beam is very fast.
   激光束的脉冲传播速度非常快。
3. 3.In order to improve the accuracy of the measurement, we need to increase the pulse propagation velocity.
   为了提高测量的准确性，我们需要增加脉冲传播速度。