Electron rockets have been around for decades, but the ability to launch hydrogen and oxygen as payloads has been a challenge.
Now researchers at the University of Arizona are working to create a high-energy version.
They say their approach could be the first step toward developing a new class of high-performance rocket engines.
“The high-intensity electron (HIE) is one of the most promising avenues to pursue for hydrogen-fueled propulsion,” said the study’s lead author, Paul D. Buehler, a postdoctoral fellow in the UA’s Department of Mechanical Engineering.
“If we could find a way to achieve a high electron density at low-density, we could potentially have a much more efficient way to accelerate hydrogen-oxygen rockets, allowing them to lift heavier payloads with less fuel.”
The researchers are using the term HIE to describe a type of high intensity electron that can be fired at extremely high temperatures.
That type of electron is a byproduct of the formation of high energy electrons in the presence of a metallic lattice, or an electronic device called a metallic ion.
“HIE is a type that can have a very high electron charge in a very short amount of time,” said Buehl, who has previously worked on a hydrogen-powered rocket called the Advanced Electron Heavy Ion (AHEI) that has been used to power satellites.
“This is very exciting because we’ve never seen such a fast and large change in electron density in the high-density state.”
The team first demonstrated their approach using an electron rocket engine.
“We tested the HIE on a solid metal target and demonstrated that we could accelerate it by at least 1,500 times its initial energy,” said co-author Ryan K. Geddes, a research scientist in the School of Mechanical and Aerospace Engineering at the UA.
“That was pretty impressive.”
The researchers used a technique called cryogenic freezing to create an ionized material, called a cryogenic alloy, which has an electron density of about one thousandth that of pure oxygen.
In a vacuum chamber, the cryogenic material was subjected to a vacuum and heated to more than 3,000 degrees Fahrenheit.
“By melting this alloy, we can increase the amount of the electron and create a very dense material that is a lot like hydrogen,” said Gedds.
“It was much more stable than pure oxygen and it is much more conductive than pure hydrogen.”
After freezing the alloy, the team cooled it by using high-temperature electrolysis to reduce the number of electrons and the amount that they could generate.
“In order to achieve this very high energy, the metal needs to be very thin,” said D.J. Tarrant, an associate professor in the Department of Chemical Engineering at Arizona State University.
“At this point, we’re going to have to do a lot of work to figure out how to make this very thin material to get it to a higher energy level.”
The technique of melting the alloy is critical because it’s the only way to make it to the desired energy level in a process that takes several weeks.
“I think the real key is making this metal thin,” K.G. said.
“To get to the low energy level, we have to get the material to very high temperatures.”
This is the first time the researchers have used this technique to create the high energy version of the high intensity HIE.
In addition to the oxygen, the material also contains hydrogen, hydrogen-oxide, and oxygen.
The researchers say the material is extremely dense at room temperature, but its high energy makes it ideal for accelerating the hydrogen.
The research team hopes to use the material for the construction of the Advanced Electrochemical Rocket for Space (AERES) program, which aims to build an orbital rocket that will be capable of launching heavier payload than a single satellite.
“Our hope is that we can build a very lightweight, very efficient, and very efficient ion engine that can fly into low Earth orbit and that is very efficient,” said K.K. Buesler.
“As soon as you put a payload into low earth orbit, you’re going a lot faster than anything else.”
The AERES program is a joint effort between the US Air Force and NASA to build a spacecraft capable of carrying astronauts to the moon.
The project has been criticized by critics because it does not include a way for future space travelers to refuel their spacecraft and is designed to be reusable.
In 2018, a proposed crewed mission to Mars was postponed.