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The ability of relativistic laser pulses to accelerate ions from foil targets has long been established. These beams, with their high current density and ultrashort duration, are essential tools in high energy density science and have great promise as an upcoming technology in accelerator physics. To best fulfill their applications, the conversion efficiency of laser to ion energy must be optimized, with the ultimate goal of tunable ion energy, yield, and other beam parameters. The acceleration of both light and heavy ions is of interest, as they each have different uses, such as neutron generation and rare isotope production.Two experiments were carried out at the Texas Petawatt laser facility. The first experiment studied the response of imaging plate detectors to heavy ions, expanding the published literature beyond light ion calibrations. Successful modeling of the imaging plate's response function is essential to determining the absolute number of ions accelerated. A comparison of all published calibrations produces an empirical estimate for ion response for any arbitrary ion as a function of atomic mass. The second experiment investigated ion acceleration from 3D printed targets, whose protruding structure increases laser-target coupling. These structures were of the "microtube" geometry, and are most effective under the right conditions of laser intensity, pulse duration, and energy. These results are then compared to experiments on similar target structures at the PHELIX and ALEPH laser facilities, which also showed enhanced ion production. A numerical study on heavy ion acceleration was also conducted, in an optimization of the generation of multiply charged titanium beams. A thickness scan on submicron targets was executed for two laser pulse lengths to determine the best performing target for each laser. In the relativistically induced transparency regime, we show that collisional ionization cannot be neglected for sufficiently long laser pulses (near pic

The Dense Plasma Focus (DPF) is a simple Z-pinch device with the ability of producing X-rays and neutrons. Neutron production from a DPF is susceptible to electrical parameters such as voltage and current, as well as mechanical parameters including electrode geometry and insulator sleeve length. Experiments that investigate three different anode geometries on a 4.6 kJ DPF device with a voltage of ~20 kV and a current of ~230kA were carried out. Two anodes with a hemispherical tip, one with and one without a hollow, were explored as well as an anode with a flat tip, hollo, and concentric slits. In order to analyze the pinches produced in these experiments, a neutron activation detector, X-ray PIN diodes, and a series of time-resolved Schlieren probing, were used. Hollow anodes create a higher neutron yield based on recent magnetohydrodynamics simulations that show the extension and dynamics of pinches in the hollow structure. Experimental evidence of extension of the pinch column is shown for the first time using the flat top hollow anode with slits. The maximum neutron yield obtained in these experiments was 1.97E ± 0.1×108 neutrons per pulse which was acquired using the hemispherical hollow anode while hard X-ray emission was observed with the hemispherical solid anode. Based on this analysis, one can conclude that anode with a hollow is optimal for neutron production while one without a hollow is prone to ablation and serves as an X-ray source.

Neutron time-of-flight (nTOF) detectors are commonly used for fast neutron detection on nuclear fusion plasma experiments in high energy density physics. The 4.6-kJ dense plasma focus (DPF) at UC San Diego can generate neutron yields of up to ~108. Two nTOF detectors radially situated at 1.3 m from the DPF are each composed of an EJ-204 plastic scintillator and an Hamamatsu R7724 photomultiplier tube. Several hundred experimental shots have been taken over the course of four different anode types. Of those, 203 shots with neutron data were selected to calibrate both nTOF detectors. A Be-activation detector generates absolute neutron yield data and has a lower detection limit of 1.1·106 neutrons. The latter is used to calibrate the signal areas in the nTOF data, and directly correlate those signal areas with the number of neutrons incident on the detector at its radius from the DPF. This preliminary analysis finds that the two nTOF detectors have approximate efficiencies of 8100 and 1700 photons per DD neutron, respectively. Further analysis can improve the correlation as well as investigate the cross-calibration between the two nTOF detectors more thoroughly.

Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range, that features the largest modelling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities. Our energy-loss data, combined with a precise target characterization based on plasma-emission measurements using two independent spectroscopy diagnostics, demonstrate a significant deviation of the stopping power from classical models in this regime. In particular, we show that our results are in closest agreement with recent first-principles simulations based on time-dependent density functional theory.

Extreme ultraviolet (EUV) lithography, the etching of fine semiconductor features with EUV light, is based on efficiently generating light of a wavelength within a narrow bandwidth around 13.5 nm by irradiating tin droplets with a laser. Simulating this process is beneficial to aid the target design and optimize the laser-plasma interaction for an enhanced EUV light output. In this work, we benchmarked the combination of the open source FLASH code and the commercially available SPECT3D against existing experimental data, showing that by stepping down the intensity by approximately a factor of two and shifting the spectra to the right by +0.55nm, the simulations provide results with a reasonable level of accuracy. Using the benchmarked settings to investigate four novel temporal pulse shapes, we found that the “step down”, “ step up” and “Gaussian ramp” pulses resulted in 1.4%, 4.0%, and 4.0% improvements in conversion efficiency respectively over their energy-equivalent square pulses. With improvements to the atomic level modeling, further benchmarking of the simulations, and the development of a robust open-source community around these two tools, we expect FLASH and SPECT3D to be the tools of choice for new researchers in EUV lithography.

Wire X-pinches have been comprehensively studied for nearly four decades as a fast (~1 ns Full-Width Half-Max: FWHM), small (~1\textmu m) X-ray source in pulsed-power experiments. Room for improvement to this array remains though, including reducing variability in source timing, size, quantity, and flux, and the presence of strong electron beam emission post-pinch that tends to doubly expose any acquired radiograph. Many of these limitations can be reduced by optimal mass-matching of the target X to the current driver in use and a reliable cross-point geometry.Addressing these two parameters, we developed a new X-pinch, and tested in on the 200kA, 150ns rise-time GenASIS driver at UC San Diego. This new X is cut from thin metallic foils using a precision laser-cutting facility which can fabricate virtually any cross-sectional mass or crosspoint configuration. The first laser-cut foil X-pinch (LCXP) experiments used Ta, and demonstrated comparable evolution and equal or superior X-ray source parameters to comparably massed W wire X-pinches (WXPs), despite markedly different initial geometry (ie a square or trapezoidal crosspoint cross-section). Subsequent Cu LCXP experiments showed that the X-ray pulse from these targets was confined to a ~2ns period in contrast with the resolvable second pulse of hard X-ray electron beam emission common in WXPs. However, spectroscopic data showed evidence of a beam source co-located with the $\geq$10% solid density, ~1keV hot pinch source. Another promising X-pinch configuration (developed at Cornell University), the hybrid X-pinch (HXP), which consists of two conical electrodes 1-3mm apart bridged by a thin wire or capillary, demonstrated predominantly single source X-pinches and less hard X-ray emission than found in WXPs. To compare all three aforementioned X-pinch configurations–wire, hybrid, and laser-cut foils–we conducted an in-depth performance study of these X’s on the GenASIS driver, representing the first time all three c

The gas-puff Staged Z-pinch (SZP) is a magneto-inertial fusion concept in which one or more annular gas-puff liners implode onto a cylindrical target of fusion fuel. This dissertation addresses three topics essential to the viability of the concept: shock preheating of the target, stability of the implosion, and scalability to multi-megaampere drivers. Shock preheating of the target is necessary because it reduces the required convergence ratio to reach fusion-relevant conditions by raising its adiabat. The strength of the shock is determined by inertial and magnetic forces acting on the target. Initial 1-D magnetohydrodynamic (MHD) simulations of SZP implosions of thin liners show that, while liner resistivity can affect the onset of shock compression, the final target adiabat is controlled by liner inertia.As in the conventional Z-pinch, the SZP liner is prone to the magneto-Rayleigh-Taylor (MRT) instability, whose growth must be sufficiently mitigated to maintain liner integrity throughout the implosion. Here, multiple mitigation mechanisms are considered. The first is inherent to a gas-puff Z-pinch liner - modes of wavelengths below a certain minimum can resistively diffuse away. 2-D MHD simulations suggest that Kr and Xe liners have a higher minimum wavelength than Ne and Ar due to their higher resistivity, and later simulations with Ne liners suggest this effect could reduce dominant mode growth below the classical rate, $\sqrt{gk}$.Two additional mechanisms are implemented: axial premagnetization, which reduces growth via field-line tension, and inclusion of a second liner, which alters the dynamics. 2-D simulations with Ne liners show that stabilization of single and double-liner configurations requires a $B_{z0}$ of 0.5 and 0.2 T, respectively. This reduction is important because there is a rapid drop-off in DD neutron yield for large $B_{z0}$ due to reduced fuel compression.Finally, a semi-analytic model is developed to assess the scalability of the SZP. A

Intense proton beams are appealing research subjects in high energy density physics and fast ignition of inertial confinement fusion as they are advantageous to isochoric heating and local energy deposition deep in the medium. A leading method for generation of proton beams utilizes high-power lasers to accelerate protons to energies over MeV. For applications, generation of these intense beams must be controlled, and understanding of the physics of beam transport in a new intensity regime is required. This thesis contains experimental findings, as well as computational studies, on the generation of intense proton beams and their transport in solid density matter. Experiments were carried out to compare proton beam focusing from different target geometries irradiated by an intense laser. Compared to a free standing target, enclosed targets show a narrower and brighter K-alpha radiation emission spot on a foil placed behind the target, indicating higher beam focusability. Numerical simulations have confirmed that the cause of the experimentally measured focusing effect is a field on the target enclosing structures. Furthermore, the long laser pulse duration (10 ps) was beneficial to keep providing radial electric fields for beam focusing. This thesis presents a simulation of the transport and energy deposition for such an intense proton beam in solid-density matter, where both collective effects and the individual proton slowing-down are taken into account in a self-consistent, dynamically coupled manner. To achieve this, a new proton stopping power module covering warm dense matter states has been implemented in the hybrid PIC code LSP where the proton stopping power is updated with the varying local target thermodynamic state at each simulation grid and time step. Detailed analyses were undertaken to comprehend the collective effects taking place in these system. As an example, a self-generated magnetic field can develop during beam transport at high current densit