Exploring the Role of Outer Liners in Implosion Dynamics and Instability Growth for Triple Gas-Puff Z-Pinches on COBRA

Gas puff Z-pinches are an important tool in high-energy-density physics, offering a promising pathway for controlled thermonuclear fusion and intense X-ray generation. The primary challenge is Magneto-Rayleigh-Taylor instability (MRTI), which degrades pinch integrity and limits compression. MRTI can be mitigated via tailored density profiling. In experiments reported here, we used a triple-nozzle gas injector on the COBRA generator (~1 MA, 220 ns rise time) to study the implosion dynamics and MRTI growth for various outer liners (Neon, Argon, and Krypton) surrounding a Ne inner liner and a Xenon-doped hydrogen target. Plasma dynamics were characterized using XUV framing cameras, soft X-ray photodiodes, a time-integrated pinhole camera, a Mach-Zehnder interferometer, optical Thomson scattering, and an X-ray spectrometer. Our findings indicate the Neon outer liner yielded 1.7x more X-rays than Argon and 3x more than Krypton. Quantitative comparison of minimum pinch radii reveals Ne OL achieved twice the radial compression efficiency vs. Ar and Kr.