Dynamics of cylindrically converging precursor plasma flow in wire-array Z -pinch experiments.

Area of Science:

• Plasma Physics
• Z-pinch dynamics
• High-energy density physics

Background:

• Precursor column formation is critical in wire array z-pinches.
• Understanding this process is key for applications like inertial confinement fusion.
• Previous models lacked detailed experimental validation.

Purpose of the Study:

• To experimentally investigate precursor column formation in cylindrical wire arrays.
• To measure diameter variation, soft x-ray emission, and density profiles during collapse.
• To compare experimental data with theoretical and simulation models.

Main Methods:

• Experiments conducted on the 1 MA MAGPIE generator.
• Utilized direct measurements of diameter variation.
• Employed soft x-ray emission and quantitative radiography.
• Analyzed data from standard and twisted cylindrical wire arrays.

Main Results:

• Identified three distinct stages: initial broad profile, rapid contraction, and slow expansion.
• Correlated x-ray emission with diameter changes, indicating nonlinear collapse driven by density and cooling.
• Measured minimum column diameters showed good agreement with pressure balance models.
• Column expansion rates provided estimates for temperature and current.

Conclusions:

• Experimental data align well with fluid and kinetic modeling.
• The study highlights the necessity of incorporating collisionless flow in early-stage models.
• Findings advance the understanding of plasma dynamics in z-pinch devices.