(I suppose that you mean supercritical state of fluid.)
Supercritical state of liquid-gas is a state that liquid state and gas state stop to exist at particular temperature and pressure.
There is only just fluid state which has both liquid and gas property and if you change the pressure or temperature just a bit, it will change to one of the state.
How to achieve supercritical state ?
The supercritical state is done at HIGH TEMPERATURE and PRESSURE.
For example, the famous CO2 fluid (used to separate caffeine from the coffee bean) is acquired at 304.1 Kelvin and 72.8 atm.
NOT: mist is a state between a gas and liquid (supercritical)Corrected:Mist is a heterogenous mixture of very tiny water droplets (liquid) 'hanging' in the air (gas).[More on supercritical fluids and the 4th state of matter, is found on the discussion page]
the example of supercritical fluid are water deep inside the earth
No. Saturn consists mostly of supercritical hydrogen and helium, in a state between liquid and gas.
Supercritical fluid extraction is now used in laboratories.
K(multiplication factor/reproduction factor) >1 (Mass of fissile material to be supercritical)
Because at room temperature it behaves like gas. Although it is in supercritical state, its density becomes very low on temperatures far above critical value, so it behaves like gas and it's not useful for extraction.
Supercritical Fractionation and Isomerization Area
supercritical
Bharat Heavy Electricals Limited (BHEL) has despatched boiler columns for the first supercritical boiler, being manufactured in India. These columns will be used for installation of BHEL-built supercritical Boilers at Barh Thermal Power Project Stage-II, located about 75 kms from Patnain Bihar
Supercritical carbon dioxide is used as a non polar solvent to extract caffeine from coffee beens. Supercritical gases are not quite gases and not quite liquids but sort of in between.
solid, liquid, gas, supercritical fluid
Autoclave Chlorine dioxide Plasma Supercritical CO2 Glutaraldehyde