Experimental study on breakdown characteristics of polymethylmethacrylate under fast pulse

A single pulse breakdown experiment was performed on polymethylmethacrylate(PMMA) using a uniform field geometry, and the breakdown strength and breakdown time delay were obtained. The applied pulse amplitude was about 230 kV, rise time 760-960 ps, pulse width 2.3-4.0 ns(FWHM), and the specimen mean thickness was 1.1 mm. The experimental result shows that as the pulse width increases from 2.3 ns to 4.0 ns，the average breakdown strength of PMMA reduces from 301 kV/mm to 276 kV/mm, the average breakdown time delay approximately has a fixed value, but the standard deviation rises under the pulse with rise time 760 ps, pulse width 2.3 ns. Finally, based on the breakdown phenomena observed by stereomicroscope, the breakdown process was analyzed.