抄録
In order to optimize the method to use both UV and IR laser in inducing a negative impulse discharge in a rod-torod electrode configuration, three kinds of techniques such as the cross-beam, the cascaded-beam and the overlappedbeam methods have been examined. In case of the cross-beam method, the two lasers were required to be simultaneously applied at a carefully controlled instant within a time range of 20 ns. It would be very difficult to use them for a long gap discharge. In case of the cascaded-beam method, although the two lasers were required to have almost the same output energy, it would be very useful to extend the guiding length. In case of the overlapped-beam method, acceleration of a leader by the overlapping was observed.
