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

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
_L
= 1.25 cm, has an average full width at half-maximum Δr
_L
= 0.50 cm, and a mass density ρ
_L
= 0.5-140 μg/cm
³
, 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
_T
= 0.80 cm, and a density ρ
_T
= 0.3-30 μg/cm
³
. The molecular deuterium can be partially ionized and accelerated out of the injector with a velocity v
_z
> 2 cm/μs by a coaxial plasma gun built into the injector.