Mixing helium with oxygen and igniting it would result in a fire, but the characteristics and behavior of the fire would be different from a typical hydrocarbon-based fire. Here's what would happen:
Helium (He): Helium is an inert gas, meaning it is chemically non-reactive under normal conditions. It does not support combustion or burn. It is lighter than air and tends to disperse quickly.
Oxygen (O2): Oxygen is a highly reactive gas that supports combustion. It is necessary for most fuels to burn. When oxygen is present in sufficient quantities, it can enhance the combustion process.
When helium and oxygen are mixed, the helium does not contribute to the combustion process. Instead, it primarily acts as a diluent, reducing the concentration of oxygen and making the mixture less reactive.
If a flame or ignition source is introduced to the helium-oxygen mixture, the oxygen component can support the combustion of other flammable materials present in the environment. For example, if there are combustible materials nearby, such as fuels or flammable gases, they may ignite and burn more vigorously due to the presence of oxygen.
However, without a readily combustible material in the environment, the helium-oxygen mixture itself would not sustain a flame or burn significantly. The helium would not participate in the combustion process and would simply disperse due to its low density.
It's important to note that mixing and igniting gases can be dangerous, and it should only be done in controlled and safe environments by trained individuals following appropriate safety protocols.