Spatially resolved measurements of load current delivery on a 14 MA, 100 ns pulsed power experiment using a line-imaging velocity interferometer
Not Available
43 PARTICLE ACCELERATORS↗
Engineering topics
McLean, Harry S.
Publications and source records attributed to McLean, Harry S..
A laser parameter study on enhancing proton generation from microtube foil targets
Abstract The interaction of an intense laser with a solid foil target can drive $$\sim$$ ∼ TV/m electric fields, accelerating ions to MeV energies. In this study, we experimentally observe that structured targets can dramatically enhance proton acceleration in the target normal sheath acceleration regime. At the Texas Petawatt Laser facility, we compared proton acceleration from a $$1\, {\upmu }\hbox {m}$$ 1 μ m flat Ag foil, to a fixed microtube structure 3D printed on the front side of the same foil type. A pulse length (140–450 fs) and intensity ((4–10) $$\times 10^{20}$$ × 10 20 W/cm $$^2$$ 2 ) study found an optimum laser configuration (140 fs, 4 $$\times 10^{20}$$ × 10 20 W/cm $$^2$$ 2 ), in which microtube targets increase the proton cutoff energy by 50% and the yield of highly energetic protons ( $$>10$$ > 10 MeV) by a factor of 8 $$\times$$ × . When the laser intensity reaches $$10^{21}$$ 10 21 W/cm $$^2$$ 2 , the prepulse shutters the microtubes with an overcritical plasma, damping their performance. 2D particle-in-cell simulations are performed, with and without the preplasma profile imported, to better understand the coupling of laser energy to the microtube targets. The simulations are in qualitative agreement with the experimental results, and show that the prepulse is necessary to account for when the laser intensity is sufficiently high.
43 PARTICLE ACCELERATORS↗
Plasma confinement system with outer electrode having liquifiable material and methods for use
An example plasma confinement system includes an inner electrode having a rounded first end that is disposed on a longitudinal axis of the plasma confinement system and an outer electrode that at least partially surrounds the inner electrode. The outer electrode includes a solid conductive shell and an electrically conductive material disposed on the solid conductive shell and on the longitudinal axis of the plasma confinement system. The electrically conductive material has a melting point within a range of 170° C. to 800° C. at 1 atmosphere of pressure. Related plasma confinement systems and methods are also disclosed herein.
Shumlak, Uri↗
Thermonuclear neutron emission from a sheared-flow stabilized Z-pinch
We report the fusion Z-pinch experiment (FuZE) is a sheared-flow stabilized Z-pinch designed to study the effects of flow stabilization on deuterium plasmas with densities and temperatures high enough to drive nuclear fusion reactions. Results from FuZE show high pinch currents and neutron emission durations thousands of times longer than instability growth times. While these results are consistent with thermonuclear neutron emission, energetically resolved neutron measurements are a stronger constraint on the origin of the fusion production. This stems from the strong anisotropy in energy created in beam-target fusion, compared to the relatively isotropic emission in thermonuclear fusion. In dense Z-pinch plasmas, a potential and undesirable cause of beam-target fusion reactions is the presence of fast-growing, “sausage” instabilities. This work introduces a new method for characterizing beam instabilities by recording individual neutron interactions in plastic scintillator detectors positioned at two different angles around the device chamber. Histograms of the pulse-integral spectra from the two locations are compared using detailed Monte Carlo simulations. These models infer the deuteron beam energy based on differences in the measured neutron spectra at the two angles, thereby discriminating beam-target from thermonuclear production. An analysis of neutron emission profiles from FuZE precludes the presence of deuteron beams with energies greater than 4.65 keV with a statistical uncertainty of 4.15 keV and a systematic uncertainty of 0.53 keV. This analysis demonstrates that axial, beam-target fusion reactions are not the dominant source of neutron emission from FuZE. These data are promising for scaling FuZE up to fusion reactor conditions.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗