Scientists from the National Institute of Laser, Plasma and Radiation Physics in the city of Magurele proposed a new method of receiving oxygen from carbon dioxide contained in Mars atmosphere using ultra-dense pulse plasma jets. In the course of their lab experiments they proved that short, but powerful plasma pulses are capable of almost instantaneous splitting CO₂ into oxygen and carbon monoxide under pressure close to natural ambient conditions of Mars.
The interest to the technology of receiving oxygen from CO₂ is directly connected with the outlook of development and future colonization of the red planet. It is very expensive from the economic and technical standpoint to deliver oxygen from Earth for long-term missions, hence, the production of vitally important substances “on site” becomes the key task. Mars atmosphere is almost 96% carbon dioxide; hence, it is viewed as the main source of oxygen for breathing, fuel and other needs of future expeditions.
Today MOXIE experiment is already in progress at the American Mars rover Perseverance; the objective is to produce oxygen from CO₂ by high-temperature electrolysis method. However, this unit requires a complicated compression and heating system and provides for a relatively limited productivity.
Romanian researchers, however, followed the other way and placed their bet not on the “slow” chemistry, but on the speed of the processes at the level of separate molecules. In traditional plasma generators (e.g., radio-frequency ones) electrons have relatively low energy and split CO₂ stage-by-stage, exciting oscillations of the molecules. Such mechanism may be energy-efficient on Earth, but given the low pressure on Mars it does not work well: the process is too slow and the significant portion of the received oxygen is successfully joining carbon monoxide again returning back to CO₂.
The situation is different in pulse plasma jet. Due to very strong currents in the short pulse in plasma, electrons with 10-13 electron-volt appear – and that is enough to break the CO₂ molecule just at once. Such direct dissociation mechanism takes only several nano-seconds. Hence, oxygen is generated practically immediately, and the reverse reaction fail to decrease its output. In the experiments performed in Magurele, oxygen was fixed 20-50 times quicker than when using radio-frequency plasma of the same power.
The study showed some very important practical regularities. Under very low pressure the maximum share of the split CO₂ is achieved, while as under 4–5 torr — the maximum mass of the received oxygen, because the system has more initial gas. If the pressure grows, the efficiency goes down, which is connected with worse conditions of electrons accelerating. These results provide understandable benchmarks for engineers working on further optimization – from electrodes geometry to the unit operation modes.
However, the proposed method has certain restrictions from the energy industry standpoint: under the pressure on Mars any plasma technology inevitably needs relatively high energy per one molecule. Nevertheless, pulse plasma jets turned out to be much more efficient other plasma-based approaches in the same conditions. In addition, the system is easily scaled from the standpoint of pulse frequency. Even though in the lab the pulses were infrequent, the calculations show that when more powerful feeding sources are used it is possible to achieve the productivity sufficient for covering the oxygen needs of human beings during reasonable time.
