What is a plasma stealth system and the principle of plasma stealth

How to achieve "plasma stealth" of the Blackbird reconnaissance aircraft? Cesium is added to the fuel, but it is not commonly used.

Plasma is a macroscopic neutralized gas larger than the length of the de bye (electric dipole moment unit), whose motion is mainly governed by electromagnetic forces and exhibits significant collective behavior. It is the fourth state of matter that appears after the three forms of solid, liquid, and gas in which matter exists. In the military, nuclear, radioisotope rays, shock waves of hypersonic vehicles, jets of rockets and jets mixed with easily ionizing components such as cesium, potassium, and sodium in fuel can form weakly ionizing plasma.

Plasma stealth technology refers to a technology that uses plasma avoidance detection systems. At present, there are two main methods for generating stealth plasma: one is to use a plasma generator to generate plasma, that is, at low temperature, the gas medium is activated in the form of gap discharge and surface discharge through the high energy provided by the power supply in the form of high frequency and high voltage

ionization to form plasma; The other is to coat a layer of radioactive isotope on a specific part of the weapon (such as a strong scattering area), and its radiation dose should ensure that the plasma cladding produced by its A-ray ionization of air has sufficient electron density and thickness to ensure the strongest absorption of radar waves. The latter is more expensive and difficult to maintain as compared to the former. Plasma can be divided into energy plasma, hot plasma and low-temperature plasma according to its heat capacity.

The basic principle of plasma stealth is to use plasma generators, generators or radioactive isotopes to form a layer of plasma cloud on the surface of weapons, and design the characteristic parameters of plasma (energy, ionization, oscillation frequency and collision frequency, etc.) to meet specific requirements, so that part of the radar wave irradiated on the plasma cloud is absorbed, and part of it changes the direction of propagation, so that the energy returned to the radar receiver is very small, making it difficult for the enemy to detect and achieve the purpose of stealth; It can also change the frequency of the reflected signal to make the enemy radar measure the wrong aircraft position and speed data to achieve stealth. It has been reported that the probability of a vehicle being detected by the enemy using this technology can be reduced by 99 .

The plasma itself is an easy target to detect, even if the opponent's radar cannot detect the target protected by the plasma, but it can still easily detect the plasma and indirectly detect the target.

As an emerging technology for target radar signature signal control, the core of plasma technology is the generation and moderate application of plasma. The so-called plasma is the gas when it is affected by some external factor (such as the shock wave of a hypersonic vehicle; jets of nuclear**, jet aircraft; Radioisotope rays, etc.), ionization generates free electrons, positive ions, and a small number of negative ions with approximately equal density. Theoretical research and experimental results show that plasma has a very significant absorption and dissipation effect on radar waves, which has attracted great attention from stealth designers.

As early as the 60s, the United States and Russia began to notice the role of plasma generated by shock waves around the aircraft, and did some exploratory studies through wind tunnel tests. It is found that the electron density of the plasma cladding on the surface of the aircraft is very sensitive to the magnitude of the flight speed. When the flight speed is in a certain range, the RCS is the smallest, and when the speed is further increased, the RCS increases rapidly.

It is also found that whether radar waves can enter the envelope, where the reflection occurs and the frequency band of absorption depend on the electron distribution and density in the envelope. Finally, it is concluded that the key to realizing the stealth of the plasma of the first system lies in how to control the electron density of the plasma cladding of the first system such as the aircraft.

With the deepening of research and the accumulation of a large number of experimental data, two typical methods that can effectively generate plasma cladding have been obtained: one is the application of plasma generator; The second is to apply an appropriate amount of radioactive isotopes (such as P210O, C242M, etc.) to specific parts of the aircraft. The advantage of the former method is that the structure does not need to be changed, it is easy to use and the stealth effect is very good, the disadvantage is that the stealth of the installation site of the plasma generator is very problematic, and the power supply power of the generator is limited.

The technical difficulty of the latter is the difficulty in controlling the radiation dose of radioisotopes. If the dose is too small, the rays produced by it will not produce electrons of sufficient density and thickness; If the dose is too large, the radar wave will be reflected back at a critical electron density in the envelope before it reaches the surface of the aircraft.

As a new stealth technology, although there are various difficulties and difficulties in its initial research and development stage, plasma technology has been highly valued by many countries in the world because it does not involve the aerodynamic characteristics, stealth and practical application of the aircraft itself, especially for a series of advantages such as easy stealth transformation of the current system. According to reports, Russia is ahead of the United States in plasma radar stealth technology, they have developed two generations of plasma equipment, and are currently developing a third. They are also preparing to open up and export the first two generations.

Other countries are also gradually getting involved in this research and application work.

Plasma stealth technology is a technology that uses plasma to avoid radar electromagnetic wave detection. As we know, the so-called plasma is when the atoms or molecules in the gas are subjected to external high-energy actions (such as the bombardment of high-energy particles or the irradiation of lasers, etc.), and some of the electrons in the atoms absorb energy and break away from the atoms and become free electrons. At this time, the components of the gas change from uncharged atoms or molecules to positive and negative ions, and the physical properties of the gas change dramatically.

Different from conventional passive stealth technology, conventional passive stealth is to reduce the possibility of being detected by enemy radar by the shape layout and absorbing materials, while plasma stealth technology belongs to active anti-radar stealth technology, like other active anti-radar stealth technology (including electromagnetic cancellation technology, radio frequency jammer with suppressive jamming and deceptive jamming radar decoy technology), plasma is relying on its own special physical properties and special effects on incident electromagnetic waves to achieve stealth purposes