Characterization of a Liner-on-Target Gas Injector for Staged Z-Pinch Experiments

Abstract

The staged Z-pinch (SZP) is a magnetoinertial fusion scheme, where a high-Z gas liner implodes onto a deuterium gas target. An accurate measurement of the initial mass distribution, both in the liner and target, is crucial to achieve the fusion-relevant conditions. This paper presents the characterization of a double-valve injector for the SZP experiment, performed on a test stand with interferometric and visible emission diagnostics. The injector produces an annular liner gas profile that is peaked at R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = 1.25 cm, has an average full width at half-maximum Δr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = 0.50 cm, and a mass density ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = 0.5-140 μg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , which is adjusted by selecting the gas species between Ar and Kr, plenum pressure, and injection timing. The target gas density is centered on the axis, has a width Δr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> = 0.80 cm, and a density ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> = 0.3-30 μg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The molecular deuterium can be partially ionized and accelerated out of the injector with a velocity v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</sub> > 2 cm/μs by a coaxial plasma gun built into the injector.