Laser-plasma accelerators recreate space radiation in the lab
Scientists led by Strathclyde University have, for the first time, recreated a key property of outer space here on Earth. Using a special type of particle accelerator, the international team has developed a way to generate the same type of space radiation that poses a threat to astronauts and spacecraft. Through the interaction of lasers and plasma, it opens the way to cheaper, more realistic testing of new technology destined for orbit.
Space is very hard on humans and machines, with all sorts of hazards that need to be defended against. One of the worst of these is radiation – especially that produced by the Van Allen belts. These two belts, situated between 1,000 km (620 mi) and 60,000 km (37,300 mi) above the Earth, are created by our planet's powerful magnetic field and help protect us against cosmic and solar radiation that would make our planet uninhabitable.
Unfortunately, this protection comes at a price and the Van Allen Belts are themselves radiation hazards that pose a threat to any spacecraft that pass through them. This means that engineers are very keen to, for example, harden electronics against radiation damage and that means finding ways to test that hardening.
As the Strathclyde team points out, the best way to do this would be to take the device into space and see what happens, but that's so expensive that it's like seeing how tough your brand new Rolex is by smashing it with a sledgehammer. It works, but it isn't cost effective. Instead, the team came up with a way to recreate the space radiation of electrons, protons and ions here on Earth.
It's already possible to create radiation in the laboratory using particle accelerators like linacs and cyclotrons, but these machines are a little too good at their job. They generate what is called a well-defined "monoenergetic electron, proton,and ion flux." In English, that means they produce very pure beams of radiation. But what space engineers want is something dirtier, with the radiation spread out over a broad band like those in the radiation belts.
To achieve this, the Strathclyde team used laser-plasma-accelerators at the Heinrich-Heine-University in Düsseldorf and at Britain's Central Laser Facility in collaboration with the National Physical Laboratory as part of a series of proof-of-concept experiments.
Laser plasma accelerators work by using very powerful electric fields formed inside plasma waves to accelerate charged particles to high energies in a very short distance. When a laser pulse is shot through this plasma, it pushes electrons in front of it in a wave. This creates relativistic, broadband radiation that duplicates that from the Van Allen belts.
The team says that the system is still under development with more experiments planned at the Strathclyde-based Scottish Centre for the Application of Plasma-Based Accelerators (SCAPA). Should the results prove promising, it could provide more access to component testing and the development of new testing procedures. In addition, it could help in the exploration of the outer Solar System.
"Our research shows laser-plasma-accelerators are viable tools for space radiation testing and are a valuable addition to conventional ground-based testing techniques," says Professor Bernhard Hidding, of Strathclyde's Department of Physics. "Further progress is expected in laser-plasma accelerator technology and this will allow the range of accurately reproducible space radiation to be further extended, to, for example, the radiation belts of other planets with magnetic fields, such as Jupiter or Saturn. These planets have much stronger magnetic fields, generating far higher energy electrons than that of Earth, but exploratory missions in these harsh radiation environments have a high scientific priority, such as investigating the possibility of water on the Jupiter moon Io."
The research was published in Scientific Reports.
Source: Strathclyde University