Microwave plasma in a vortex is like a kitchen mixer that simultaneously heats and stirs the gas. In the reactor, the gas is swirled, and microwaves heat it to thousands of degrees, tearing carbon dioxide molecules apart. Scientists created a computer model of such a reactor to understand how pressure affects the process.

At a pressure of 150 mbar (about 7 times less than atmospheric), CO₂ splitting reaches its maximum. But raise the pressure to 400 mbar, and efficiency drops by more than half. The reason lies in a race between two processes: the decomposition of CO₂ into carbon monoxide and oxygen, and the reverse reaction that reassembles CO₂ from these pieces. At high pressure, molecules collide more often, and the reverse reaction wins.

The model showed that the vortex not only holds the plasma but also returns some of the gas to the hot zone, giving it a second chance to split. However, near the top wall of the reactor, the gas cools too slowly, and there CO manages to turn back into CO₂. At 400 mbar, this loss becomes critical: more than 60% of the CO formed is lost.

Scientists now know exactly where and why the product is lost, and they can modify the reactor design to cool the gas faster and preserve more CO. This is a step toward practical use of plasma for CO₂ recycling.