We report the plasma pressure reached inside the central plasma column of a sheared-flow-stabilized Z-pinch using Thomson scattering measurements. Building on previously reported experimental results and the analysis methods established for the high temperature and moderate density plasmas generated on the FuZE device, we show evidence of a central plasma region with higher electron temperature and density, which is consistent with a pinch behavior. Elevated electron temperatures up to 2.25 ± 0.8 keV and densities up to (4.9±0.2)×1017 cm−3 are observed to temporally coincide with the fusion neutron production from the plasma. Reconstructed plasma pressure profiles highlight the presence of a several millimeter-wide column with elevated pressure whose location varies shot-to-shot. The plasma pressure rises as neutron production from the deuterium plasma increases, reaching a peak value of 2.6 kBar. This peak value is consistent with a radially force-balanced pinch equilibrium model based on the measured ∼320 kA pinch current. Complete datasets were obtained at two axial locations, 10 and 20 cm axial position from the tip of the central electrode, which corroborate the estimated neutron source axial lengths.

The sheared -flow -stabilized Z pinch concept has been studied extensively and is able to produce fusionrelevant plasma parameters along with neutron production over several microseconds. We present here elevated electron temperature results spatially and temporally coincident with the plasma neutron source. An optical Thomson scattering apparatus designed for the FuZE device measures temperatures in the range of 1 -3 keV on the axis of the device, 20 cm downstream of the nose cone. The 17 -fiber system measures the radial profiles of the electron temperature. Scanning the laser time with respect to the neutron pulse time over a series of discharges allows the reconstruction of the T e temporal response, confirming that the electron temperature peaks simultaneously with the neutron output, as well as the pinch current and inductive voltage generated within the plasma. Comparison to spectroscopic ion temperature measurements suggests a plasma in thermal equilibrium. The elevated T e confirms the presence of a plasma assembled on axis, and indicates limited radiative losses, demonstrating a basis for scaling this device toward net gain fusion conditions.

A diagnostic for extreme ultraviolet spectroscopy was fielded on the sheared-flow-stabilized (SFS) fusion Z-pinch experiment (FuZE-Q) for the first time. The spectrometer collected time-gated plasma emission spectra in the 5-40 nm wavelength (30-250 eV) range for impurity identification, radiative power studies, and for plasma temperature and density measurements. The unique implementation of the diagnostic included fast (10 ns risetime) pulsed high voltage electronics and a multi-stage differential pumping system that allowed the vacuum-coupled spectrometer to collect three independently timed spectra per FuZE-Q shot while also protecting sensitive internal components. Analysis of line emission identifies oxygen (N-, C-, B-, Be-, Li-, and He-like O), peaking in intensity shortly after maximum current (>500 kA). This work provides a foundation for future high energy spectroscopy experiments on SFS Z-pinch devices.

Zap Energy is pursuing a sheared-flow-stabilized Z-pinch as the core of a fusion reactor technology. Recent experimental efforts have demonstrated currents higher than 600 kA and electron temperatures higher than lkeV. Some of the open questions for this concept are how the neutron yield scales with current, how the power supply bank couples to the dynamic plasma load, and how the cathodes survive under repeated discharges of several hundred klloJoules, among other questions. To help answer these questions, the Zap Energy Theory and Modeling team is using the WARPXM code, a discontinuous Galerkin modeling framework developed at U. Washington. Using a two-dimensional MHD model coupled to a circuit solver, we show scaling of neutron yields as a power law with current for several different voltage configurations, and discuss the implications for cathode erosion. We also discuss coupling of WARPXM with PIC models, benchmarking of WARPXM with NIMROD, and acceleration of WARPXM with GPU.

Zap Energy is a private fusion energy company developing the sheared-flow-stabilized (SFS) Z-pinch concept for commercial energy production. Spun out from the University of Washington, these experimental and computational efforts have resulted in devices with quasi-steady DD fusion yields above 10(9) per pulse. These devices support scaling toward energy breakeven on existing devices as well as beyond to commercially relevant engineering fusion gains. This article discusses the strategy behind Zap's development path, which is derived directly from the engineering and scientific elegance of the confinement method. Without need for external confinement or heating technologies, the SFS Z pinch relies on plasma self-organization. This compact magnetic confinement technology could, in turn, provide the basis for a cost-effective fusion power plant, vastly reduced in complexity from its competitors.

The sheared-flow-stabilized Z-pinch concept is on a path to commercialization at Zap Energy. Recent experiments on the Fusion Z-pinch Experiment (FuZE) device corroborate expected plasma stability and thermonuclear fusion reaction rates. Experimental campaigns are underway to increase the pinch current, the stable plasma duration, and the DD fusion neutron production. The next-generation device FuZE-Q is currently undergoing commissioning and will begin operation at current levels where scientific breakeven-equivalent conditions are expected in the near future. The Z-pinch configuration offers the promise of a compact fusion device owing to its simple geometry, unity beta, and absence of external magnetic field coils.In addition to a robust experimental program pushing plasma performance toward breakeven conditions, Zap Energy has parallel programs developing power handling systems suitable for future power plants. Technologies under development include high-average-power repetitive pulsed power, high-duty-cycle cathodes, and liquid-metal wall systems. High-level features of the conceptual power plant core design are elaborated and compared with other approaches to fusion energy.

We report the first optical Thomson scattering measurements inside a high electron temperature (≳1 keV) and moderate electron density (mid 1016 cm-3) plasma. This diagnostic has been built to provide critical plasma parameters, such as electron temperature and density, for Advanced Research Projects Agency-Energy-supported fusion-energy concepts. It uses an 8 J laser at 532 nm in 1.5 ns to measure the high frequency feature of the Thomson scattering profile at 17 locations along the probe axis. It is able to measure electron density from 5 × 1017 cm-3 to several 1019 cm-3 and electron temperatures from tens of eV to several keV. Here, we describe the design, deployment, and analysis on the sheared flow stabilized Z-pinch machine at Zap Energy named FuZE. The probe beam is aimed at an axial distance of 20 cm from the central electrode and is timed within the temporal envelope of neutron emission. The high temperature and moderate density plasmas generated on FuZE lie in an unconventional regime for Thomson scattering as they are between tokamaks and laser-produced plasmas. We described the analysis considerations in this regime, show that the electron density was below 5 × 1016 cm-3 at all times during these measurements, and present a sample shot where the inferred electron temperature varied from 167 ± 16 eV to 700 ± 85 eV over 1.6 cm.

Shear-flow stabilized Z-pinch plasmas generated at the fusion Z-pinch experiment (FuZE) are designed to achieve high densities and temperatures for nuclear fusion. Time-resolved electron temperature of the pinch is measured using a soft x-ray triple foil diagnostic. Pairwise ratios of the x-ray intensities attenuated through titanium foils of varying thicknesses are calculated to determine the electron temperature assuming bremsstrahlung x-ray radiation from a Maxwellian distribution of electrons. Electron temperatures above 1 keV are observed for several pulses. These temperature measurements are compared to other fusion-relevant diagnostics such as the neutron yield, ion temperature, and pinch current.

The goal of this work is to investigate the behavior of alpha particles in a Z-pinch plasma configuration. A Z pinch is one of the oldest plasma fusion configurations, but Z pinches have always suffered from a series of instabilities that limit their performance. Recently, sheared flow stabilization has resulted in significant stability gains, with some pinches lasting up to 10 us (several thousand linear instability growth times). Zap Energy is currently operating a sheared-flow-stabilized Z pinch: the Fusion Z-pinch Experiment (FuZE). However, as these devices reach higher rates of fusion, the resulting fusion by-products may play a key role in the plasma energy balance.

Zap Energy Inc. is rapidly developing the technology to produce fusion-relevant z-pinch plasma discharges stabilized via sheared flow. The Z-pinch configuration offers the promise of a compact fusion device owing to its simple geometry, unity beta, and absence of external magnetic field coils. In addition to a robust experimental program pushing plasma performance towards breakeven conditions [1] , Zap Energy has parallel programs developing power handling systems suitable for future power plants including: high-average-power repetitive pulsed power, high-duty-cycle cathodes, and liquid metal wall systems.

The sheared-flow-stabilized (SFS) Z-pinch concept, developed at University of Washington with LLNL collaborators, is now on a path to commercialization at Zap Energy Inc. Recent experiments corroborate expected thermonuclear fusion reaction rates, as the discharge current is scaled towards compact reactor conditions. The Fusion Z-pinch Experiment (FuZE) employs high-power-handling electrodes, flexible gas injection, and independently switched capacitor bank modules to tailor the discharge current and gas distribution to establish stabilizing sheared flow and pinch current. An extensive set of diagnostics provide key measurements, with collaborators from LANL, LLNL, UBC, among others. Experimental campaigns are under way to increase the pinch current, stability duration, and DD fusion neutron production. In 2021, we achieved record pinch currents, 500 kA, record electron temperature, > 2 keV, and record ion temperature, > 2.5 keV. These efforts aim to scale the pinch current, plasma density, and plasma temperature to reach scientific breakeven by 2023 in the next-generation device FuZE-Q, which is currently being commissioned.

We present results for a photonic microwave resonator designed and fabricated at 17.4GHz with a record high Quality factor (Q = 26,400) at room temperature over a mode volume smaller than one cubic wavelength. The cavity is uniquely designed to have its electric field concentrated in air, which allows for efficient coupling to free space and facilitates interactions with gaseous atomic systems and fluids.

ATRAP has made many important improvements since CERN's Antiproton Decelerator (AD) was restarted in 2006. These include substantial increases in the number of positrons (e+) and antiprotons (Pbars) used to make antihydrogen (Hbar) atoms, a new technique for loading electrons (e-) that are used to cool Pbars and e+, implementation of a completely new, larger and more robust apparatus in our second experimental zone and the inclusion of a quadrupole Ioffe trap intended to trap the coldest Hbar atoms produced. Using this new apparatus we have produced large numbers of Hbar atoms within a Penning trap that is located within this quadrupole Ioffe trap using a new technique which shows promise for producing even colder atoms. These observed Hbar atoms resolve a debate about whether positrons and antiprotons can be brought together to form atoms within the divergent magnetic fields of a quadrupole Ioffe trap.

Slow antihydrogen (H) is produced within a Penning trap that is located within a quadrupole Ioffe trap, the latter intended to ultimately confine extremely cold, ground-state H[over ] atoms. Observed H[over ] atoms in this configuration resolve a debate about whether positrons and antiprotons can be brought together to form atoms within the divergent magnetic fields of a quadrupole Ioffe trap. The number of detected H atoms actually increases when a 400 mK Ioffe trap is turned on.

Ten-nanosecond pulses of photoelectrons liberated by intense UV laser pulses from a thin gold layer are captured into a single-component plasma that is ideally suited to cool antiprotons (p¯) for antihydrogen (H¯) production. Up to a billion electrons are accumulated using a series of laser pulses, more than are needed for efficient p¯ cooling in the large traps now being used for loading p¯ for H¯ production. The method is demonstrated within an enclosed vacuum space that is entirely at 4 K, and is thus compatible with the exceptional cryogenic vacuum that is desirable for the long-term storage of antihydrogen. The pitfalls of other electron accumulation methods are entirely avoided, including the particle heating and declining efficiency of field emission point loading, and the heat load and contamination of thermionic emission methods.

Ten-nanosecond pulses of photoelectrons liberated by intense UV laser pulses from a thin gold layer are captured into a single-component plasma that is ideally suited to cool antiprotons (¯ p) for antihydrogen ( ¯ H) production. Up to a billion electrons are accumulated using a series of laser pulses, more than are needed for efficient ¯ p cooling in the large traps now being used for loading ¯ pf or ¯ H production. The method is demonstrated within an enclosed vacuum space that is entirely at 4 K, and is thus compatible with the exceptional cryogenic vacuum that is desirable for the long-term storage of antihydrogen. The pitfalls of other electron accumulation methods are entirely avoided, including the particle heating and declining efficiency of field emission point loading, and the heat load and contamination of thermionic emission methods. © 2007 Elsevier B.V. All rights reserved.