Scaling and enhancement of non-thermal line emission on z to hν ∼ 22 kev

We report on experiments demonstrating the transition from thermally-dominated K-shell line emission to non-thermal, hot-electron-driven inner-shell emission for z pinch plasmas on the Z machine. We find preferential scaling of non-thermal line emission for atomic number Z=42 and higher (hν ≥ 17keV). Initial experiments with Mo (Z=42) and Ag (Z=47) have produced kJ-level emission in the 17-keV and 22-keV Ka lines respectively. We will discuss the electron beam properties that could excite these non-thermal lines. Recent experiments have also attempted to control non-thermal K-shell line emission by modifying the load hardware. Initial indications are that altering the cathode design can increase the 17 keV Mo Ka emission and shorten the x-ray rise time.