[Answered] What is Nuclear Fusion? What are the major challenges in harnessing energy from the nuclear fusion process? Briefly comment on the progress made in this regard. 

Nuclear Fusion is the process by which two light atomic nuclei combine to form a single heavier one while releasing massive amounts of energy. For nuclear fusion, nuclei need to collide with each other at very high temperatures, exceeding ten million degrees Celsius, to enable them to overcome their mutual electrical repulsion. 

Every star in the universe, including the sun, produces energy through nuclear fusion. In the core of the Sun hydrogen is being converted into helium while producing large amounts of energy. 

Scientists have been making efforts to build a fusion nuclear reactor to harness energy for several decades, but there are many challenges 

• Extremely high Temperatures: Fusion is possible only at very high temperatures, of the order of a few hundred million degrees Celsius, creating such extreme temperatures is difficult.  
• Tolerant material required: The materials that will make up the reactor need to be able to withstand such huge amounts of heat. This creates complication in building the reactor. At present the best material available are tantalum carbide and hafnium carbide; materials that can withstand temperatures of nearly 4000 degrees Celsius. 
• Controlling the plasma: At such high temperatures, matter exists only in the plasma state, which tends to expand very fast, and is extremely difficult to handle and work with. 

• Sustaining the reaction in controlled manner: The amount of energy produced from fusion is very large about four times as compared to nuclear fission reactions. The equipment to control this release of energy is still in experimental stages.  

The benefits of fusion reaction are immense apart from generating much more energy, fusion produces no carbon emissions, the raw materials are in abundant supply, it produces negligible radioactive waste compared to fission, and is considered much safer. 

Given the benefits of fusion energy, it is considered the future of energy. There are several ongoing efforts to harness energy from the nuclear fusion process. The biggest effort in creating a fusion reactor is the International Thermonuclear Experimental Reactor (ITER). 

• The ITER is a collaboration of 35 nations, including India, launched in 1985. It is to build the world’s largest tokamak (device which uses a powerful magnetic field to confine plasma) to prove the feasibility of fusion at a large-scale. 
• The deadline for its first experimental run has been extended several times, with current timeline, it is expected to become operational only in 2035. 
• Still, ITER is only an experimental project. The energy it will produce is about 500 MW and would not be in the form of electricity that can be used. 

The deployment of fusion energy for electricity generation for our everyday needs might take another few decades after ITER becomes operational. It needs concerted efforts from all countries to expedite the development of nuclear reactors.