Gas puff Z-pinches are intense sources of X-rays and neutrons but are highly susceptible to the magneto-Rayleigh-Taylor instability (MRTI). MRTI mitigation is critical for optimal and reproducible yields, motivating significant attention toward various potential mitigation mechanisms. One such approach is the external application of an axial magnetic field, which will be discussed here in the context of recent experiments on the Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno. In these experiments, an annular Kr gas liner is imploded onto an on-axis deuterium target with a pre-embedded axial magnetic field $B_{z0}$ ranging from 0 to 0.3 T. The effect of $B_{z0}$ on the stability of the Kr liner is evaluated with measurements of plasma radius, overall instability amplitude, and dominant instability wavelength at different times obtained from time-gated extreme ultraviolet pinhole images. It was observed that the external axial magnetic field does not affect the implosion velocity significantly and that it reduces the overall instability amplitude and the presence of short-wavelength modes, indicating improved pinch stability and reproducibility. For the highest applied $B_{z0}=0.3$ T, the stagnation radius measured via visible streak images was found to increase. These findings are consistent with experiments reported in the literature, but here, the ${\mathrm{B}}_{z0}$ required for stability, ${\mathrm{B}}_{z0}=0.13\hspace{0.17em}{I}_{pk}/R_0$ (where I_pk is the driver peak current and R₀ is the initial radius), is lower. This could be attributed to the smaller load geometry, both radially and axially. Consistent with other experiments, the cause of decreased convergence cannot be explained by the additional axial magnetic pressure and remains an open question.

We present the first experimental measurement of temperature and density of a warm dense plasma produced by a pulsed power driver at the Nevada Terawatt Facility (NTF). In the early phases of discharge, most of the mass remains in the core, and it has been challenging to diagnose with traditional methods, e.g. optical probing, because of the high density and low temperature. Accurate knowledge of the transport coefficients as well as the thermodynamic state of the plasma is important to precisely test or develop theoretical models. Here, we have used spectrally resolved non-collective X-ray Thomson scattering to characterize the dense core region. We used a graphite load driven by the Zebra current generator (0.6 MA in 200 ns rise time) and the Ti He-α line produced by irradiating a Ti target with the Leopard laser (30 J, 0.8 ns) as an X-ray probing source. Using this configuration, we obtained a signal-to-noise ratio ~2.5 for the scattered signal. By fitting the experimental data with predicted spectra, we measured T = 2±1.9 eV, ρ = 0.6±0.5 gr/cc, 70 ns into the current pulse. The complexity of the dense core is revealed by the electrons in the dense core that are found to be degenerate and weakly coupled, while the ions remain highly coupled.

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 RL = 1.25 cm, has an average full width at half-maximum Δ rL = 0.50 cm, and a mass density ρL = 0.5-140 μg/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 Δ rT = 0.80 cm, and a density ρT = 0.3-30 μg/³. The molecular deuterium can be partially ionized and accelerated out of the injector with a velocity vz > 2 cm/μs by a coaxial plasma gun built into the injector.

The effect of alkali metal chlorides on the viscoelastic behavior and yielding properties of silica suspensions was studied through creep-recovery and dynamic oscillatory tests with stress control. Then, the viscoelasticity of the pulps was correlated with the silica zeta potential, aggregate size, and the percentage of cations adsorbed on the surface of the ore. The results indicate that larger cations are more prone to adhere to the silica surface, which increases the number of ionic bonds that bind the particles. This generates stronger particle networks and a greater agglomeration of particles, especially those smaller than 10 µm. As the size of the bare cations increases, the rheological response provides higher values of yield stress, complex viscosity, and viscoelastic moduli, but in turn, pulps undergo minor deformations under the application of stress. Dynamic oscillatory tests suggest structural changes, with the phase angle following the inverse relationship with the bare cation size, indicating that the liquid-like character of the pulps increases as the size of the cations increases.

The Collective Thomson scattering technique has been implemented to study the stagnation of a single liner gas-puff. The plasma parameters are determined by theoretically modelling the scattering form factor in combination with Bayesian inference to provide the set of the most probable parameters that describe the experimental data. Analysis of the data reveal that incoming flows are able to interpenetrate partially. Estimation of the mean free path shows a gradual transition from a weakly collisional to a collisional regime as the plasma gets to the axis. Furthermore, we find that the ion energy at $$\mathrm{r}=2.5\,\mathrm{mm}$$r = 2.5 mm is $${13.6}_{-0.9}^{+1.0}\,\mathrm{keV}$$13.6 - 0.9 + 1.0 keV and is mostly kinetic in nature and represents $${98}_{-9}^{+10} \%$$98 - 9 + 10 % of the total energy. This kinetic energy is far greater than the value on axis of $${3.7}_{-0.5}^{+0.4}\,\mathrm{keV}$$3.7 - 0.5 + 0.4 keV which is $${84}_{-14}^{+15} \%$$84 - 14 + 15 % of the total energy. Energy transfer to the electrons and radiation losses are found to be negligible by this time. A possible explanation for this energy imbalance is the presence of an azimuthal magnetic field larger than $$\sim 4.7\,\mathrm{T}$$∼ 4.7 T that deflect the ions vertically. The uncertainties quoted represent 68% credible intervals.