Suppression of the ablation phase in wire array Z pinches using a tailored current prepulse.

Area of Science:

• Plasma physics
• High-energy-density physics
• Pulsed power applications

Background:

• Wire arrays are used for plasma implosions.
• Instabilities and trailing mass often disrupt implosion symmetry and efficiency.
• Controlling initial wire conditions is crucial for stable implosions.

Purpose of the Study:

• To investigate a new wire array configuration for thin shell-like implosions.
• To understand the effect of a current prepulse on wire array dynamics.
• To suppress instabilities and trailing mass during plasma implosions.

Main Methods:

• Utilized a cylindrical wire array setup.
• Applied a current prepulse (~5 kA, ~25 ns) followed by a current-free interval (~140 ns).
• Delivered a main current pulse (~1 MA) to drive implosion.

Main Results:

• The prepulse heated wires, causing them to expand and eliminate dense wire cores.
• Suppressed the ablation phase, resulting in an accelerating implosion.
• Observed no trailing mass, indicating improved implosion efficiency.
• Inferred Rayleigh-Taylor instabilities seeded by μm-scale wire surface perturbations.

Conclusions:

• The absence of a dense wire core is critical for stable, thin shell-like implosions.
• The prepulse technique effectively modifies wire array dynamics for improved implosion performance.
• This configuration offers a pathway to controlled plasma implosions with reduced instabilities.