Chinese scientists create a plasma stealth device to take military aircraft off the radar

Scientists and engineers have created a new plasma stealth device that focuses on shielding key areas instead of an entire aircraft
It could be a game-changer for military aircraft that now rely on radar-absorbent coatings and geometric designs for stealth

Science

Stephen Chenin Beijing

Published: 8:00pm, 19 Feb 2024

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A new-generation plasma stealth device that can make almost any military aircraft vanish from a radar screen is claimed to have been developed by a team of scientists and engineers from western China.

Unlike its predecessors, which generate a cloud of plasma draped over a plane, this innovation can be tailored to fit a sensitive section of a military aircraft – areas like the radar dome, cockpit or other spots that are most prone to enemy radar detection.

This “closed electron beam plasma stealth device”, which focuses on protecting key areas instead of the entire aircraft, can be switched on at a moment’s notice to fool radar operators.

It has many advantages such as “simple structure, wide power adjustable range and high plasma density,” Tan Chang, a scientist involved in the project, wrote in a peer-reviewed paper published in the Chinese Journal of Radio Science in December.

This novel technical solution could soon find its way onto various military aircraft to meet China’s rapidly growing demand for superior military capabilities, said Tan and his colleagues from the Plasma Technology Centre of the Xian Aerospace Propulsion Institute under the China Aerospace Science and Technology Corporation, the nation’s biggest aerospace defence contractor.

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Plasma, composed of electrically charged particles, interacts with electromagnetic waves in a unique way. When electromagnetic waves – such as those emitted by radar – interact with plasma, they cause the particles to move rapidly and collide, dissipating the waves’ energy and reducing the strength of the reflected signal.

This interaction converts the energy of the electromagnetic waves into mechanical and thermal energy of the charged particles, diminishing the waves’ strength and subsequently weakening the radar signal reflected back. Even a conventional fighter jet, not designed for stealth, can significantly reduce its radar signature with this plasma stealth device – potentially game-changing in aerial combat.

The concept of plasma stealth technology traces back to the Cold War era, where both the United States and the Soviet Union poured resources into its research and development. However, due to technological constraints, it never progressed beyond the laboratory phase. Today’s stealth aircraft, like the F-22 and F-35, rely on radar-absorbent coatings and distinctive geometric designs for stealth, often at the cost of aerodynamic performance. The F-22, for instance, struggles in close combat, while the F-35 cannot maintain supersonic cruise speeds. These stealth fighters also come with a hefty price tag.

China’s foray into plasma stealth came late. In the early days, some experts believed that if Western countries could not achieve a breakthrough, China would not succeed either. However, as the Chinese hi-tech sector flourished, with a booming electronics and telecommunications industry, its military also made leaps in electromagnetic control technology.

Many believe the plasma technology will become crucial in future military conflicts. Photo: EPA-EFE/US Air Force

Plasma can change the frequency of reflected signals, causing enemy radar to detect incorrect data for aircraft position and speed, and obtain false signals. It can also serve as an invisible “shield” against high-power microwave weapons.

An increasing number of Chinese military researchers believe that this technology will play a crucial role in future confrontations between major military powers.

Two types of plasma stealth devices have already been put to the test, according to Tan’s team. One device coats the aircraft’s radar-prone areas with a radioactive isotope, which emits high-energy rays that ionise the surrounding air. This creates a plasma layer, thick and dense enough to cover the surface and scatter radar signals. The other device uses high-frequency high-voltage electricity to activate and ionise the gas medium outside the aircraft, creating a plasma region.

“Both of these methods for achieving stealth via low-temperature plasma have undergone flight tests and proven successful,” Tan’s team wrote in the paper.

Chinese scientists have even extended this technology into space, using an alkali metal jet plasma generator to form a plasma cloud, achieving stealth for weapon platforms like intercontinental missiles or military satellites, they added.

However, the existing plasma stealth technology has some drawbacks. When exposed to the open environment, the plasma is difficult to shape precisely, and maintaining a consistently high density is also a challenge. Gaps in the plasma can allow electromagnetic waves to reflect back, revealing the aircraft’s position.

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Many researchers in China, including the air force, are now trying to build on existing achievements and develop a closed plasma stealth technology, according to Tan’s team. This would confine the plasma within a sealed cavity, making it easier to generate high-density plasma and change its characteristic parameters to absorb multi-band electromagnetic waves. This would give additional protection to vital areas targeted by enemy radar, “such as the radar dome and pilot cockpit”, the scientists said.

Tan’s team has developed one such device that uses electron beam discharge to generate large confined areas of plasma, a method that was disclosed to the public for the first time. Compared to other reported techniques like closed radio frequency plasma discharge devices, this approach separates the plasma from the generator, providing greater flexibility in cavity design to fit different aircraft structures.

The team said that plasma generated by electron beams offers superior adjustability of physical properties, higher energy efficiency, reduced power demands from the aircraft, and lighter weight, making it ideal for practical applications.

Prototype tests conducted on the ground have displayed the feasibility of their design. However, not everyone can build this machine, as there are many technical challenges behind its seemingly simple structure. For instance, accurately measuring plasma within the cavity poses a significant hurdle with existing methods, according to the Chinese researchers.

The project’s development involved numerous technological innovations, some of which were shared by Tan’s team in the paper, including techniques for regulating inert gas density within the cavity.

They emphasised that adapting this technology to specific engineering applications requires careful consideration of the aircraft’s structural characteristics.

“We anticipate the real-life implementation of this technology in China soon,” Tan and his colleagues added.