Double Plasma Shock After Pinching in Table-Top Plasma Focus Device

A study regarding the characterization of plasma sheath evolution after pinch time in a tabletop size plasma focus (PF), is presented in this work. A 300 J energy Mather-type PF device1,2 is used to carry out the experiments. Shadowgraphy probing using laser pulses of 150 ps duration is the diagnostic implemented for the plasma sheath evolution. Time-series of shadowgrams are used for the characterization of the plasma dynamics in later times after pinching. The expansion of the plasma sheath front in PF is found to be intersected axially by a secondary bubble-like shockwave front. The characteristics of the main and the secondary front dynamics are evaluated and correlated with the experimental parameters. A case of double shockwave is also presented. The obtained results are compared with relevant works and discussion concerning the source of the shockwave is made.