The invention relates to a movable
discharge electrode, in particular to a movable
discharge electrode applied to capillary tube
discharge soft X-
ray lasers. The movable discharge
electrode aims at solving the problem that in an existing method for changing
gain media, current waveforms obtained under the condition of different
gain medium lengths are not coincident with a main
pulse current waveform, and the inherent thought that in the prior art, the length of a capillary tube is changed or the length of an electrode is changed is eliminated. An elastic steel wire is arranged on the electrode, the effect that the electrode can be fixed at any position in the capillary tube is achieved, and then the aim of changing the
gain media is achieved. As when the electrode is fixed at any position in the capillary tube, the total length of a
plasma column is the difference of the length of the capillary tube and the length of the electrode, it is guaranteed that the total length of the
plasma column is kept unchanged, and then the effect that under the condition of different gain medium lengths, the
pulse current waveforms same as the main
pulse current waveform are obtained is achieved. The movable discharge electrode is suitable for a capillary tube discharge test.