Abstract:A numerical model for the calculation of the variable inductance during the current-sheet (CS) evolution in plasmafocus (PF) devices is presented. The model represents the CS by an articulated surface of many coaxial conical elements accelerated by the Lorentz force while collecting the mass swept in their paths. The numerical results are validated against the measurements of the time-varying inductance in a 6-kJ PF device, showing good agreement.
“…To get a sensible interpretation of the images and glean useful information out of them, we perform numerical calculations of the evolution of the current sheet using the code CShock 26 , 27 , which is based in a 2D model that was verified with several experiments, working particularly well in tracking the shaping of the current sheet 25 , 39 . Figure 5 Experimentally measured current (dashed line) compared to the numerically calculated current by means of the CShock code.…”
Section: Resultsmentioning
confidence: 99%
“…Validated numerical models based in the snowplow scenario are currently available to assist in the interpretation of the experimental data from the point of view of physical conservation principles. In particular, in the present work we exploit the 2D computer code CShock, which has shown excellent capabilities to simulate the rundown phase [25][26][27] .…”
Plasma Foci are pulsed coaxial discharges with numerous radiation applications and interesting scientific phenomena. Although the physics answered much of the processes involved in these discharges, many related fundamental questions still remains doggedly unresolved. One of the obstacles to deeper knowledge is the scarcity of reliable experimental data. This work presents an elaborate experimental assessment of the electron density in the rundown phase of a 400 J Plasma Focus operating with hydrogen. The rundown of the plasma sheath is basically a hypersonic shock wave between two coaxial electrodes accelerated by the Lorentz force, and it is important to control the pinch formation. The electron density of the passing sheath is measured by means of the Stark broadened hydrogen alpha emission with spatial and temporal resolution. The experimental data is post-processed using Bayesian posterior probability assessment. The results are conflated with the numerical model CShock to construe an educated explanation of the sheath behavior during the rundown. In particular, it is possible to reckon the formation of a toroidal instability reported in previous experiments, and to estimate the plasma sheath temperature (4–20 eV) and velocity (62.5 km/s) at this stage.
“…To get a sensible interpretation of the images and glean useful information out of them, we perform numerical calculations of the evolution of the current sheet using the code CShock 26 , 27 , which is based in a 2D model that was verified with several experiments, working particularly well in tracking the shaping of the current sheet 25 , 39 . Figure 5 Experimentally measured current (dashed line) compared to the numerically calculated current by means of the CShock code.…”
Section: Resultsmentioning
confidence: 99%
“…Validated numerical models based in the snowplow scenario are currently available to assist in the interpretation of the experimental data from the point of view of physical conservation principles. In particular, in the present work we exploit the 2D computer code CShock, which has shown excellent capabilities to simulate the rundown phase [25][26][27] .…”
Plasma Foci are pulsed coaxial discharges with numerous radiation applications and interesting scientific phenomena. Although the physics answered much of the processes involved in these discharges, many related fundamental questions still remains doggedly unresolved. One of the obstacles to deeper knowledge is the scarcity of reliable experimental data. This work presents an elaborate experimental assessment of the electron density in the rundown phase of a 400 J Plasma Focus operating with hydrogen. The rundown of the plasma sheath is basically a hypersonic shock wave between two coaxial electrodes accelerated by the Lorentz force, and it is important to control the pinch formation. The electron density of the passing sheath is measured by means of the Stark broadened hydrogen alpha emission with spatial and temporal resolution. The experimental data is post-processed using Bayesian posterior probability assessment. The results are conflated with the numerical model CShock to construe an educated explanation of the sheath behavior during the rundown. In particular, it is possible to reckon the formation of a toroidal instability reported in previous experiments, and to estimate the plasma sheath temperature (4–20 eV) and velocity (62.5 km/s) at this stage.
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