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The power of imitation: scientists from the Russian Federation have brought the sending of expeditions to Mars closer
Russian engineers have created a device to simulate cosmic radiation in terrestrial conditions. This is a low-intensity gamma radiation source. The device is designed to test the radiation resistance of microelectronics, which is designed for long-term operation in different orbits as part of research satellites, observatories or manned spacecraft. The device is safe for personnel and has small dimensions, which allows it to be used in small laboratories and design bureaus. The development is useful for testing the component base in the preparation of unmanned expeditions to Mars and deep space, experts noted.
How to simulate cosmic radiation on Earth
Radiation is one of the main factors that pose a threat to microelectronics in space. Therefore, when creating orbital equipment, appropriate protection measures are provided, and equipment is tested before launch.
However, testing in large research facilities is expensive, which increases the cost of space missions. To solve this problem, specialists from the Institute of Physical and Technical Problems (IFTP, part of the Automated Process Control and Electrical Engineering division of Rosatom State Corporation) and Roscosmos enterprises have created a miniature installation for testing microcircuits for radiation resistance.
The device is designed to test individual electronic components, not the entire hardware. In accordance with its dimensions and functional purpose, the device was named "GNOME" — "Gamma-ray low-intensity irradiator of microcircuits".
— The device includes a source of low-intensity gamma rays that simulate the effects of electrons and protons from outer space, and a camera where the test sample is placed. The isotope caesium-137 is used as the active element. The energy of its radiation is 0.662 MeV. This is stronger than X-ray rays, but weaker than cobalt—60, an isotope used in medical equipment," Alexander Smirnov, director of the IFTP, told Izvestia.
The use of caesium-137 made it possible to reduce the mass and dimensional characteristics of the installation and ensure the protection of personnel during operation. Also, for safety reasons, the walls of the chamber are made of radiation-resistant shielding materials, and the channel for connecting power cables to the samples is a maze that prevents the spread of gamma particles. Thus, the GNOME installation design fully protects personnel from exposure to gamma radiation in all modes of operation and storage.
Alexander Smirnov noted that the radiation dose rate in the chamber of the device is in the range of 0.01 rad/s. Such radiation levels correspond to the actual conditions of space flight. The volume of the test chamber is 1 liter. It is made in the form of a cube with dimensions of 10x10x10 cm. At the same time, small dimensions and safety for personnel allow the device to be used in the process of developing space technology in small laboratories and design bureaus.
Rad is a unit of measurement used in radiation dosimetry. It determines the level of absorbed dose of ionizing radiation. One rad is equal to the power at which 1 g of matter transfers the energy of 100 erg.
100 erg is comparable to the kinetic energy of a mosquito in flight or a meteorite with a mass of 1 mg, which moves at a speed of 10 km/s. This is a small quantity on a human scale, but significant in the microcosm (molecular processes, radiation physics).
In nuclear physics and elementary particle physics, electron volts (eV) are used. If we conditionally compare the units of measurement, then the energy of the gamma-ray quantum of the isotope caesium-137 (0.662 MeV) will be about a million times less than the energy of a flying mosquito. At the same time, it is precisely because of their small size and high ionizing ability that gamma quanta pose a danger to living cells and microelectronics.
According to the specialist, tests are carried out in the installation from 1 to 10 weeks. The duration depends on the type of sample being examined. Several dozen tests have been carried out since the device was put into operation. Testing is performed at the level of 1-10 stolen (kilorad) absorbed doses.
The device does not require electricity, since isotope sources emit radiation on their own. This allows testing to be carried out around the clock. The device provides the ability to adjust different radiation modes by placing the boards closer or further to the radiation source.
What types of radiation are present in space
As the developers explained, the degree of damage to microelectronics depends on the specific product, technology and manufacturing quality. Mainly due to the effects of gamma particles, the electrical parameters of the microcircuits go beyond acceptable values or stop working.
At the same time, radiation in space is heterogeneous. For example, small doses are present in low orbits (up to 2 thousand km), but if the device is located outside the satellite or it is a small device with thin protection, then the amount of radiation accumulated by the electronics may be higher.
According to scientists, the most severe orbits are from 2,000 to 4,000 km high due to the large number of high-energy protons. In geostationary orbit, electrons with energies up to several MeV abound, but their influence is relatively easily eliminated by a small mass protection.
Experts noted that the South Atlantic anomaly (an area with a low magnetic field intensity), as well as solar flares directed towards the Earth, which are characterized by increased proton densities, pose a certain danger. They cause single radiation effects in microcircuits with small topological norms, and also make an additional contribution to dose effects. Another type of extreme conditions is prolonged space flights, during which instruments are exposed to prolonged radiation exposure.
— Electronics require materials with high stability. If ionizing radiation disrupts the crystal structure of a semiconductor, its electrical characteristics change, which can lead to partial degradation or complete inactivity of the device," Anatoly Petrukovich, director of the Space Research Institute of the Russian Academy of Sciences, told Izvestia.
According to him, both physical means (for example, thickened device walls and radiation-resistant chip housings) and software methods are used to protect electronic components. The latter include algorithms for self-diagnosis during flight and isolation (or restart) of damaged elements.
In addition, devices with an enlarged topology are being designed for space purposes, which is less susceptible to the effects of high-energy particles. Ground tests also play a significant role in protecting microelectronics.
The main danger for instruments in orbit is represented by corpuscular radiation — streams of particles (electrons, protons and heavy nuclei), the expert noted. It is difficult to recreate such conditions on Earth, so gamma rays and X-rays and tables of their conversion into cosmic radiation are usually used for testing.
Anatoly Petrukovich added that there is no consensus in the scientific community about the correctness of applying terrestrial radiation safety standards (developed for gamma radiation) to astronauts, for example, during flights to Mars, where corpuscular radiation prevails. Nevertheless, such tests are justified for unmanned vehicles whose behavior in space has been well studied.
— Russian developers are creating some of the world's highest quality systems for protecting electronics in space, both from ionizing radiation and from heavy contaminated particles. This is largely achieved through the use of CNI technologies (technology for manufacturing semiconductor devices based on the use of a three-layer substrate with a silicon–dielectric – silicon structure. — Izvestia). One of the tasks of the presented equipment is to test such protective equipment," said Viktor Enns, Deputy General Director of the Research Institute of Molecular Electronics.
He explained that such technologies prevent parasitic processes (for example, current leakage), reduce heating and reduce exposure to radiation.
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