In the relentless pursuit of harnessing the power of nuclear fusion, a team of scientists led by R.A. Ryan at Zap Energy in Everett, Washington, has made a significant breakthrough. Their recent study, published in the journal Nuclear Fusion, sheds new light on the behavior of neutron energy in a sheared-flow-stabilized Z pinch, a configuration that holds promise for commercial fusion energy.
The Z pinch is a type of plasma confinement system that uses a strong electrical current to compress and heat a plasma, potentially reaching the conditions necessary for fusion. However, achieving a stable and efficient Z pinch has been a long-standing challenge. The team at Zap Energy has been operating the Fusion Z Pinch Experiment (FuZE) at increasingly higher input power, resulting in larger fusion neutron yields and higher plasma currents.
“The key to our success has been the ability to operate at higher input powers, which has allowed us to achieve average plasma currents of 370 kA and D-D fusion neutron yields of approximately 40 million neutrons per discharge,” says Ryan. This increase in power and yield has enabled more detailed measurements of neutron energy isotropy, providing stringent limits on possible contributions from beam-target fusion.
The study reveals that the energy of deuteron beams in the FuZE device is less than 7.4 ± 5.6 (stat) ± 3.7 (syst) keV. This finding is crucial because it helps to rule out the possibility of significant beam-target fusion, which could complicate the interpretation of the data. The researchers have also developed a more accurate characterization of the detector response, reducing the number of free parameters in the fit of the neutron energy distribution. This improves the confidence in the forward-fit method and enhances the overall reliability of the measurements.
One of the most exciting aspects of this research is the time-dependent measurement of neutron energy isotropy. For the first time, the team has resolved the isotropy over time, indicating that possible deuteron beam energies may increase at late times. This suggests the potential growth of m = 0 instabilities at the end of the main radiation event, but it confirms that the majority of neutron production exhibits isotropy consistent with a thermonuclear origin.
The implications of this research are far-reaching. If the Z pinch can be stabilized and made efficient, it could pave the way for a new generation of fusion reactors that are more compact and cost-effective than traditional tokamaks. This could revolutionize the energy sector, providing a nearly limitless source of clean, sustainable power.
“We are excited about the potential of this technology,” says Ryan. “The ability to achieve high neutron yields and understand the underlying physics is a critical step toward making fusion energy a reality.”
The study, published in the journal Nuclear Fusion, marks a significant milestone in the quest for controlled nuclear fusion. As the world continues to search for sustainable energy solutions, the work of Ryan and his team at Zap Energy offers a glimmer of hope for a future powered by the same forces that drive the stars.
