Under the Lab Coat | X, Y, Z-Pinch

Nuclear fusion is one of climate's biggest moonshots. Flow Z-Pinch Lab helps advance this technology towards commercial viability.

Welcome to Under the Lab Coat, where we’ll breakdown the technology advancements explored and investigated at Universities to start and accelerate the next climate moonshot. 

To effectively mitigate against further temperature rises the world needs scalable, zero-emission, abundant energy. Nuclear fusion has long been on a path to commercial viability as the holy grail of clean energy production. In today’s post we’ll look at the Flow Z-Pinch Lab at University of Washington which is working to advance nuclear fusion research. The lab is led by Professor Uri Shumlak who specializes in plasma physics including confinement methods for fusion energy. 

Background

In nuclear energy both fission and fusion are thrown around a lot. Fission, which is used by existing nuclear power plants, is splitting a heavy, unstable nucleus into two lighter nuclei; uranium is split into smaller atoms, such as ceasium, barium, xenon, and others, which releases both radiation and heat that produce enormous amounts of electricity. However, this type of nuclear energy is not without significant, serious downsides. Nuclear fission reactors are expensive to construct, have a radioactive waste byproduct that must be safely stored for thousands of years, and have both environmental and public safety concerns that were only made worse by events such as Three-Mile Island, Fukushima, and Chernobyl. Fusion combines two light nuclei into one larger nucleus; commonly two hydrogen isotopes are collided to form helium. Fusion reactors mitigate many of the concerns and risks of fission reactors including they are cheaper to build, do not produce radioactive waste, and once the reaction conditions aren’t meant the reaction stops preventing runaway reactions (i.e. meltdowns). However, it takes immense upfront energy to start and maintain the reaction, which is one blocker to creating a commercial solution that nets electricity.    

Technology

There are three main conditions to start and maintain a nuclear fusion reaction:

• Temperature: The minimum temperature required is at least 100 million degrees Celsius. The hydrogen isotopes must collide at extremely high speed to overcome repulsive forces (Coulomb barrier). To reach the required particle speed extremely high temperatures are necessary. 

• Density: If the atoms are not close enough together then collisions will not occur and therefore nuclear fusion will not occur. Fusion reactors use magnetic fields to confine the plasma to increase particle density causing a higher collision rate. 

• Time: The temperature and density conditions must be met for a sufficiently long time for the hydrogen isotopes to collide. Additionally, due to the energy required to achieve and maintain the minimum temperature and density conditions, the reaction must continue for a long enough time such that enough energy is generated to net electricity. 

The Flow Z-Pinch Lab investigates the density component required to meet fusion reaction conditions through alternative methods to traditional electromagnetic coils. Their research includes investigating the feasibility and performance of adding axial flows to improve plasma stability for applications in fusion energy and space propulsion. 

What is Z-Pinch? Z-Pinch is a plasma containment method where, instead of using magnetic coils, an electric current is applied to the plasma to generate the electromagnetic field that confines and compresses it. The upside to this method is that it is cheaper than using magnetic coils and the setup is simpler. However, the downside is stability issues that cause distortions where the plasma can escape and affect the integrity and damage the setup. 

To address the stability issues, The Flow Z-Pinch Lab introduced a sheared axial flow. By adding the axial motion the surface of the plasma is continuously smoothed, stopping the bulges and kinks from forming, and mitigates the instability issues. 

Product

Two key factors to developing a commercially viable fusion reactor are reducing the enormous amount of energy to start and maintain the fusion reaction as well as the reactor cost and longevity. The Flow Z-Pinch Lab has demonstrated that nuclear fusion is possible without large magnetic field coils, which reduces the reactor size and cost. Additional investigation is required to compare the upfront energy requirement between these methods at scale. The Flow Z-Pinch Lab has a spin-off company, Zap Energy, that is developing commercial fusion applications which was co-founded by Uri Shumlak. We’ll dive into Zap Energy, its technology, and business model in the next post.