Breakthrough in 4π ion emission mechanism understanding in plasma focus devices

Abstract

Ion emission angular distribution mechanisms in plasma focus devices (PFD) have not yet been well developed and understood being due to the lack of an efficient wide-angle ion distribution image detection system to characterize a PFD space in detail. Present belief is that the acceleration of ions points from “anode top” upwards in forward direction within a small solid angle. A breakthrough is reported in this study, by mega-size position-sensitive polycarbonate ion image detection systems invented, on discovery of 4π ion emission from the “anode top” in a PFD space after plasma pinch instability and radial run-away of ions from the “anode cathodes array” during axial acceleration of plasma sheaths before the radial phase. These two ion emission source mechanisms behave respectively as a “Point Ion Source” and a “Line Ion Source” forming “Ion Cathode Shadows” on mega-size detectors. We believe that the inventions and discoveries made here will open new horizons for advanced ion emission studies towards better mechanisms understanding and in particular will promote efficient applications of PFDs in medicine, science and technology.

Discovery of Third Possible Ion Generating Source in 4π Plasma Focus Device Space

“…A dense plasma focus device (PFD) emits high-energy ions generally believed to be emitted from the anode top within a small solid angle around the z axis, for which generation mechanisms are yet to be understood, although different theories and models have been advanced (Sadowski et al 1988; Antanasijević et al 2003; Soto 2005; Lee and Saw 2013). Recently, in a chain of emission studies of ions such as hydrogen, deuterium, and helium in a Mather-type 3.5 kJ PFD (Sohrabi et al 2016; Sohrabi 2017, 2018; Sohrabi and Zarinshad 2020; Soltani et al 2019; Sohrabi et al 2020a and b; Sohrabi and Soltani 2021), it was hypothesized and discovered that ions in PFD space are emitted in near 4π geometry from the “anode top” as intense “point ion source” and from “anode cathodes assembly” (ACA) as a “line ion source” with radial run-away ions, based on which the “Two-sources Ion Emission Model” was proposed (Sohrabi et al 2016; Sohrabi et al 2020a). These sources are strong enough to be used for different applications in 4π PFD space such as those used for expulsion for developing “Ionology Art for Art Ionology Methods” (Sohrabi and Zarinshad 2020).…”

“…The rationale behind understanding this mechanism is the application of panorama mega-size polycarbonate cylindrical ion image detectors (MS-PCID) processed by panorama mega-size electrochemical etching (MS-ECE) ion image processing systems (Sohrabi et al 2016; Sohrabi 2017, 2018). In all our studies, “ion cathode shadows” (ICS) have been formed on 4π ion emission images on the detector, distinctly well observed by the unaided eyes on the MS-PCIDs.…”

“…The formation of ICSs is due to the fact that each cathode well shadows ions bombarding it by the “anode top” and the “anode cathodes assembly,” preventing them from reaching MS-PCID placed at a distance behind cathodes (Sohrabi et al 2016; Sohrabi 2017, 2018; Sohrabi et al 2020a and b; Soltani et al 2019); thus, no ions are expected to bombard the detector on the shadow site. However, it was discovered unexpectedly that ion tracks at high densities have been formed on each shadow easily observed by unaided eyes and photographed, called “On Shadow Ion Tracks” (OSIT).…”

“…OSITs have been formed in most of our detailed studies, some of which were presented. It seems that ions forming the OSITs are generated in addition to what generated from the “anode top” and “anode cathodes assembly” (Sohrabi et al 2016; Sohrabi 2017, 2018; Sohrabi and Zarinshad 2020; Soltani et al 2019; Sohrabi et al 2020a and b; Sohrabi and Soltani 2021). This understanding of formation of OSITs on ICSs is still at the infancy stage and requires further experimental and theoretical investigations for confirmation of this third ion source or finding other less probable mechanisms.…”

“…The ACA consists of a central copper anode (13.3 cm length, 2.0 cm diameter) with a solid flat-end copper cone anode top (0.7 cm diameter top, 3.3 cm height, and 2.0 cm cone base) and six copper cathodes (13 cm length, 0.9 cm diameter) placed on a 1-cm-thick copper base. More details on the PFD used have been reported previously (Sohrabi et al 2016;Sohrabi 2017Sohrabi , 2018. A Pyrex glass tube with an effective 48 mm active length was used as the insulator sleeve.…”