Insulator Surface Conditioning Effects on X-Ray Yield of a 10 kJ-Scale Dense Plasma Focus.*

The insulator sleeve plays an important role in Dense Plasma Focus (DPF) current sheath dynamics, which can affect production of X-rays and neutrons. We have conducted experiments with 250 kA current and 2.5 $\mu $s rise time to investigate the effect of insulator sleeve conditions on X-ray production. A variety of borosilicate insulator sleeves with smooth and rough surfaces have been used. Insulators with the smoothest surfaces resulted in the highest soft X-ray yield to date when filled with Ne between 0.1 and 1.0 torr. Introducing surface roughness has a detrimental effect on X-ray yield and can substantially delay the X-ray burst.