What is the fourth state of matter, how it can be used as fuel in future?

Plasma is known to be the fourth state of matter. It is entirely different when compared with three well known basic states of matter. Solid, liquids and gas are three states of any substance which we feel around us. But out there away from earth into space, matter exists in form of plasma state. By nature, the plasma does not exist itself on earth. However, it can be created in a certain condition and advanced equipments. From the concept of temperature and pressure relation to the state of matter. We have an idea on the condition that occurs when a change is made in temperature and pressure of matter. For example, its physical transfer from one state to another state. Solid ice turns to water and water to steam when the temperature is increased by supplying heat to it at a fixed pressure. Similarly, a phase change occurs in vice versa conditions.

When the gas of any element is heated further.  Eventually rising its temperature so that the particles are ionised forming an ionised gas. Ionization by temperature increase leads to the gas state that has an equal number of negative and positive charged particles. The gas in this state is called plasma. The temperature of plasma would be around 100,000oC and an example of ionised gas is, H2 —> H+ + H+ + 2e here hydrogen molecule splits into individual hydrogen atom with a positive charge and it opposite charged particles electrons in equal number.

Plasma’s made by man are mercury and sodium vapour lamps, glow tubes, arc welders etc. Producing plasma deals with high energy consumption during one of the steps in the process. Of course, it is the electrically neutral state with no net electrical charge to attain this it requires the vast amount of energy which will activate the electron to jump away from it nucleus region.

Methods that help to produce the plasma the fourth state of matter and supply enough heat

Thermal productionDc-discharge
Beam injectionAc and rf discharges
Electron beamHot emitting electrodes
Photo ionisationPulsed discharged, capacitor discharge, inductive discharge which is known as shock waves
Contact heatingHot or emitting electrodes
Plasma beamCold electrodes
FlamesCold electrodes
Energetic neutral beamIon or electron cyclotron resonance

By applying vacuum and collisional interaction plasma is generated at laboratories. Plasma becomes a fuel which can produce energy for a long duration without interruption, in a controlled thermonuclear fusion. It can make space travel easier by replacing the present rocket engines with rocket propulsion systems built with plasma rocket engines.

Present stage nuclear fusion reactors use fuels in the plasma state.