Influence of coupling between two wires on electromagnetic radiation produced by Z-pinch

We have measured X-ray, optical and microwave radiations from two parallel wires driven by a current rising to 220 kA in 100 ns. The experimental results imply that they are generated by different radiation mechanism. X-ray is generated by thermal radiation which is proportional to ohmic heating of wires. Optical radiation is from thermal emission and line emission, but microwave radiation is produced by non-thermal radiation. The dependence of radiation on distance between two wires demonstrates that increasing the coupling between two wires can enhance non-thermal radiation, but is detrimental to thermal radiation. For driving condition of 100 kA per wire used in our experiments, the critical distance where the two wires decouple is approximately 10 mm. It appears that the coupling between wires plays a fundamental role in electromagnetic radiation produced by Z-pinch.