After-Pop! Inside the Z Machine: The Most Powerful Pulse on Earth

Full Transcript

[00:00:00] Danielle Allen: This After Pop is brought to you by the Nuclear Talent Scout. Looking for your next step in Nuclear. Nuclear Talent Scout connects top talent with companies building our energy future. Register today at nucleartalentboost.com because your next opportunity could already be waiting.

Welcome to the after pop. In our previous episode, we got to talk with Ryan Zerpa, a Division one Purdue University swimmer and nuclear engineer.

Over the summer, Ryan did an internship at Sandia National Laboratories. So now we're gonna go into something that he spoke of within that episode, the Z Machine. Imagine a machine for a few billions of a second unleashes more power than all of the electric grids on Earth combined. That's the Z machine at Sandia built not to power cities, but to recreate the immense heat pressure and x-ray intensity of stellar interiors, planetary cores, and nuclear detonations in those fleeting moments, scientists can test materials, probe fusion technologies, and validate computer models for nuclear security.

So what is the Z machine? Why was it built and what's it for? There are three intertwined motivations. First, national security and the nuclear stockpile stewardship As nuclear weapons age, we want to know how materials behave under extreme conditions, temperature, pressure, shock, those types of things. The Z machine lets scientists simulate those conditions in a controlled lab setting.

Next, high energy density, physics, and basic science. It's a tool for exploring matter under extreme states, like I said, in stars giant planets or astrophysical explosions.

Pretty cool.

And lastly, fusion, as well as future energy research. Because it can compress heat and confined plasmas at extreme rates. It's used in experimental fusion approaches,

notably magnetize, linear inertial fusion to try and hit conditions where fusion yields more energy than input.

In short, it's an extreme environment created to push the boundaries across defense material science and fusion.

Now we're gonna go into kind of how it works. Sort of

Imagine you have a tiny balloon of gas. If you press it slowly, the gas leaks and the heat dissipates. But if you slam your hands together fast the gas compresses heats and reaches extreme conditions before it can escape the Z machine is like that, but hyper accelerated and electrified.

Now we'll move into the steps of how it works. First, it stores energy. The Z machine charges up a bank of capacitors over two minutes

Storing around 10 megajoules. But what does that mean? 10 megajoules is about 2.4 kilograms or five pounds of TNT.

Next discharge in a flash, AKA pulsed power. When everything is ready, the stored energy is dumped into a few tens to hundreds of nanoseconds. That's billionths of a second that concentrates the energy in time producing gigantic, instantaneous power on the order of 80 Terawatts. But what's 80 Terawatts? 80 Terawatts is. 80 trillion watts.

For context, the entire planet's electrical grids produce around 25 terawatts at any given moment. That means for a few billions of a second the Z machine's. Pulse power outshines all human electricity production combined. That's insane.

Three Z pinch, implosion magnetic compression. The high current flows through a load. Often a fine wire array, a metal cylinder or another structure. The current generates a magnetic field, which exerts an inward pinching force on the plasma.

This implodes the material inward compressing and heating it drastically. This is the Z pinch concept. Current is moving along the Z axis to produce a radial pinch Z pinch.

Four x-ray burst and extreme environment as the implosion peaks, enormous densities, temperatures, pressures, and X-ray fluxes are achieved. The target may emit a burst of x-rays and researchers measure how materials behave under those stresses.

Five diagnostics and data in that view. Nanosecond moment, a battery of diagnostics. X-ray detectors, spectrometers, particle detectors, captures signatures, everything from temperature, density, radiation, and shocks. That data helps validate computational models. And test hypothesis about fusion and material behavior.

Reset and repeat after a shot components are refurbished, reset, and the cycle repeats. The Z machine typically fires 200 shots per year.

I think of it this way, you know, in those superhero movies when the hero is about to take off or flight, they slowly bend down, building up all of this potential energy, and then in an instant they take off. A sonic boom is heard, dust is flying all around.

And usually some kid with an ice cream cone is looking at Superman flying in the air.

But with the Z machine, there is a sensory impact. You can actually feel it during a firing. Sandia engineers report that shockwaves from the electromagnetic pulse and rapid air displacement can be felt and heard miles away. The entire facility rumbles like a small earthquake. Some workers describe the effect as a low frequency boom.

Not dangerous, but unmistakable

So what are some of the challenges and caveats with doing this type of research?

First instabilities and mixing. Plasmas are famously unstable.

Just check out the Rayleigh Taylor instability plasma turbulence, things like that. Maintaining symmetry and preventing mixing is a major engineering challenge in mag lift configurations, for example. Avoiding liner breakup and controlling instabilities is crucial. Short confinement time and fast disassembly. Because things are compressed so fast, the plasma tends to fly apart very quickly. The fusion burn must occur before the system disassembles.

That's why pulses, magnetic fields and preheating schemes are tightly timed.

Scaling to net energy gain. So far, the Z machine is not a commercial fusion device. It's a research tool achieving break even where fusion output is, greater than energy input is extremely hard.

The additional complexity of capturing and sustaining the fusion output, handling heat and doing that repeatedly is non-trivial.

Lastly, wear repeatability and cost. The extreme forces. Shockwaves and mechanical stresses on the device components require refurbishing and careful design.

The cost per shot and operational overhead can be pretty high.

So how does the Z machine relate to the commercial market?

Here are some recent advances. With the First Light Fusion experiment, they recently used the Z machine to test their amplifier technology and achieve record pressures around 10 times the pressures at the Earth's core.

Next ongoing development of future versions. Sandia is exploring upgrades to allow higher shot rates and better performance.

Then there's the Z Fundamental Science Program. It's where academic and industry groups can propose experiments on the Z to explore new regimes of high energy density physics. Thank you so much for listening to the After Pop, where we break down. What the heck is a Z machine? In the blink of a cosmic eye, the Z machine stabs a target with electrical power far beyond everyday comprehension.

Every shot is a fleeting theater of extremes. Plasma squeezed to stellar intensities, x-rays, screaming outward, and atoms push to the brink. Yet for all of its power, Z is not a power plant. It's a microscope on extremes. A place where physics is pushed, where materials crack. Energies collide, and all of our models are stress tested.

When fusion becomes practical. It may be because we first tamed a machine like Z and understood the chaos behind the pulse.

You've been listening to Naked Nuclear. If you've enjoyed this episode, please share it with a friend. The next shot could light the path to new energy or deeper discovery. Until next time, stay curious.