Aug 30th 2021

Too Cool for School: US University Traps Cold Plasma

Sometimes, giving something away means getting something better in return. That principle can hold true even for the tiniest elements. When gathered hydrogen atoms give away their electrons en masse, they become plasma: a dense, powerful, substance that lies within stars such as our sun. When materials undergo the frenetic phase change into a hot or cold plasma, they become by their very nature difficult to control, challenging to study — and increasingly important to understand.

Holding the Sun in Your Hand

Safely capturing ultra-hot plasma is a sort of a scientific holy grail. It’s the key to understanding not only Earth’s power system but also cosmic power systems. Ultra-hot plasma affects how every star behaves. And stars led to every form of life as we know it. They continue to affect our daily lives via space weather, such as radiation, solar flares and coronal mass ejections, to name a few. Space weather creates auroras, threatens astronauts and global communications and — in a twist that pits electrons against each other — occasionally takes out large urban power grids, according to the Solar and Heliospheric Observatory.

While the need to predict space weather is pressing, at 10^8 degrees Kelvin, ultra-hot plasma confined in nuclear reactors is a little too hot for observation equipment to easily handle. However, recent developments indicate that hope for understanding this extreme matter may live at the other end of the temperature spectrum.

Chilled Out

In March, a laboratory at Houston’s Rice University managed to capture hot plasma’s chilly cousin. Using one laser to slow down strontium gas and another to hammer off its electrons, physicists first created 0 degrees Kelvin plasma, as ScienceNews reports, then captured it using magnetic fields. The resulting material existed for only a fraction of a second — but long enough to leave a literal mark on the field of physics in the form of an image.

That picture is what made this experiment different from previous ultracold plasma attempts. Magnetic fields interfere with optical sensors. As a result, no one could successfully image ultracold plasma trapped in a field magnetic. Before it could blink out of existence like some sort of mythical jinn, Rice research group members Killian, Gorman and Warrens set up a kind of speed trap. Like a highway patrol officer trying to ticket cars, they shot light like a “radar gun” at the plasma. They then measured the plasma’s doppler effect on the scattered light. The result was a glowing image of their ball of plasma suspended in the middle of field.

As tricky as it is to measure, the substance that Rice University’s Ultracold Atoms and Plasmas Lab created, then effectively bottled, might be the key to unlocking both knowledge and power. Because they are slowed to a small fraction of usual plasma speed, ultracold plasmas might offer humankind a close look at the rarefied states of matter hidden in the heart of Jupiter, white dwarfs and other hard-to-reach places.

It’s also an opportunity to compare the results of plasma simulations with plasma created, as it were, in vitro. And it could allow us to experiment on increasingly efficient and effective ways to control plasma user lasers and magnetic fields. Ultracold, ultraslow-moving plasmas made on demand might fast-track our ability to improve nuclear power, increase plant safety and decrease the carbon footprint — possibly, by orders of magnitude.

Plasma, Plasma Everywhere

These findings are all the more relevant because, over the last half century, plasmas have slowly crept into everyday lives. They exist quietly in layers of advanced technology, such as the pixels of high-definition television screens and microscopic layers of radiation-resistant satellite materials. And of course, they play a critical role in nuclear reactors.

Within these human-built stars, electrons are separated from their host atoms before the atoms are fused together to generate power. The newly ionized atoms flow into glowing plasma, which fusion reactors must contain using powerful magnetic fields or high-powered lasers. Proper hydrogen plasma containment using either technique consumes vast amounts of energy and eats away at the efficiency of nuclear power stations.

The efficiency of nuclear energy affects life on a local, national and global scale. Ninety-four nuclear power plants currently produce 20% of U.S. energy, according to the Nuclear Energy Institute (NEI). These plants also produce the majority of low-carbon-footprint energy. Increasing the efficiency of high-energy plasma containment would be a boon not only to people living in the 28 states that depend on nuclear power but also to millions more around the world.

Improving plasma containment and nuclear energy efficiency would require a more thorough understanding of plasma behavior at extreme temperatures — and the Rice University work may be a small step in that direction.

By Fire or Ice

The ability to readily control the flow of extreme plasma like a traffic light remains the stuff of future science. For now, regular cold plasma can be found chilling in various commercial products. Cold plasma is currently being used to sterilize surfaces and in high-speed, advanced technology combustion. As a surgical tool, cold plasma can cut through skin to remove cancerous growths. The current work on ultracold plasma conducted at Rice University is less like developing a new scalpel and more akin to giving birth to a tiny star — one that can be created, studied and allowed to flicker in and out of existence as required.

As humankind’s ability to create and control ultracold plasma improves, so too does the possibility that we will master the flow of plasma energy that comes to us from above and that we create here below. For while time stops for no one who isn’t moving at the speed of light, energy — at least when it comes from plasma — is something that we’re increasingly bringing to a halt.

Are you interested in science and innovation? We are, too. Check out Northrop Grumman career opportunities to see how you can participate in this fascinating time of discovery.