Particles Emission From Tungsten Conical Wire Array Z-Pinches

Negatively biased Faraday cups are used to detect fast traveling particles emitted by a tungsten conical wire array in the axial direction. The conical wire array is composed by 16 equally spaced tungsten (W) wires of 25
$\mu \mathrm{m}$
each used as load of the pulsed power driver. Also, the conical array dynamics is monitored using UV/XUV imaging of the self-emission of the plasma in the side-on direction. The experiments are performed in the Llampudken1 generator which delivers ~ 350 kA in~ 350 ns at different background pressures. Results indicate axial emission of MeV ions regardless the background pressure. Since different background pressures have different mean free paths for neutral-ion collisions, these energetic ions are able to interact with the background gas producing the ionization of it at pressures above 10–
⁴
Torr. This ionization is measured by the detection of electrons preceding the ions signals on the Faraday cups. According to time-of-flight measurements the emission of these ions is made during the ablation phase of the conical wire array. In addition, some experiments include a transverse electric field in the path where the particles are propagating. These experiments indicate different ionic species in the particle outflow with ionization higher than five. When comparing these observations with the dynamics observed with UV /XUV imaging, it can be suggested that the ions and the dense jet are different phenomena. The observation of fast outflow of particles from a conical wire array and possible ejection mechanisms will be shown and discussed.