https://scitechdaily.com/fusion-breakth ... n-degrees/
No, I'd hazard it was stymied by lack of funding because it was a threat to the Big Boys.In the nine decades since humans first produced fusion reactions, only a few fusion technologies have demonstrated the ability to make a thermal fusion plasma with electron temperatures hotter than 10 million degrees Celsius, roughly the temperature of the core of the sun. Zap Energy’s unique approach, known as a sheared-flow-stabilized Z pinch, has now joined those rarefied ranks, far exceeding this plasma temperature milestone in a device that is a fraction of the scale of other fusion systems.
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A new research paper, published this month in Physical Review Letters, details measurements made on Zap Energy’s Fusion Z-pinch Experiment (FuZE) of 1-3 keV plasma electron temperatures — roughly the equivalent of 11 to 37 million degrees Celsius (20 to 66 million degrees Fahrenheit). FuZE is the simplest, smallest, and lowest cost device to have achieved it.
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Zap Energy’s technology is based on a simple plasma confinement scheme known as a Z pinch, where large electric currents are channeled through a thin filament of plasma. The conducting plasma generates its own electromagnetic fields, which both heats and compresses it. While Z-pinch fusion has been experimented with since the 1950’s, the approach has largely been stymied by how short-lived its plasmas are, a problem Zap has solved by applying a dynamic flow through the plasma, a process called sheared-flow stabilization.
Now, just to entice, up till now Zap Energy was doing testing at 500 kA. Its next-generation FuZE-Q is designed for 650 kA because the team’s modeling predicts Q=1 (breakeven) around 650 kA of current. So stay tuned. BUT, Zap Energy plans to use tritium as its fuel. That’s a BIG problem since FuZE doesn't appear to offer a path to creating more. Stay tuned.“The dynamics are a wonderful balancing act of plasma physics,” explains Levitt. “As we climb to higher and higher plasma currents, we optimize the sweet spot where the temperature, density, and lifetime of the Z pinch align to form a stable, high-performance fusing plasma.”
A healthy pinch
Fusion researchers measure plasma temperatures in units of electron-volts and can measure the temperature of the plasma’s ions (nuclei) and electrons separately. Since the ions are more than a thousand-fold heavier than the electrons, the two components of the plasma can heat and cool at different rates. Since the ions are what ultimately need to be heated to fusion temperatures, plasma physicists often worry about situations where cold electrons limit ion heating, like ice cubes in a hot soup. The electrons in the FuZE plasma, however, were shown to be as hot as the ions, indicating that the plasma is in a healthy thermal equilibrium.
Further, Zap’s detailed measurements show that electron temperatures and fusion neutron production peak simultaneously. As neutrons are a primary product of the fusing ions, these observations support the idea of a fusing plasma in thermal equilibrium.
“The results in this paper and further tests we’ve done since, all paint a good overall picture of a fusion plasma with room to scale toward energy gain,” says Uri Shumlak, co-founder and Chief Scientist at Zap Energy. “Working at higher currents we’re still seeing sheared flow extending the Z-pinch lifetimes long enough to produce very high temperatures and the associated neutron yields we’d predict from modeling.”
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Unlike the two mainstream fusion approaches that have been the focus of the majority of fusion research in recent decades, Zap’s technology does not require expensive and complex superconducting magnets or powerful lasers. “Zap tech is orders of magnitude less expensive and quicker to build than other devices, allowing us to iterate rapidly and produce the cheapest thermal fusion neutrons out there. Compelling innovation economics are vital to launching a commercial fusion product on a timescale that matters,” said Benj Conway, CEO and co-founder of Zap.
In 2022, the same time these results from FuZE were collected, Zap commissioned its next-generation device FuZE-Q. While early results from FuZE-Q are still forthcoming, the device has a power bank with ten times the stored energy as FuZE and capacity to scale to much higher temperatures and densities. Meanwhile, parallel development of power plant systems is also underway.
