The arc reactor makes Iron-Man possible. This is Tony’s greatest creation. It not only gives him power but also acts as a magnet which keeps the shrapnel away from his heart. It is essentially his life support.
Creation of Arc Reactor
Howard Stark created the 1st prototype of the arc reactor, which drew power through unstable palladium core in head quarters of Stark Industries. But it was imperfect because the reactor was made with the help of limited technology of his time.
There is a possibility that the reactor was created using the Tesseract. Howard found the tesseract while looking for Steve Rogers. He studied it during his time at the S.H.I.E.L.D. The arc reactor was made from the knowledge gained from the study of the cube. The goal of Senior Stark was to develop a cleaner alternative to the nuclear energy.
Origin of the Tesseract
The cube of limitless power came from Asgard. According to Red Skull’s description, the Asgardians designed cube to harness the true power of the space stone it contained. These infinity stones can be wielded or their power can only be harnessed with something. For example Loki used the sceptre to control the mind stone, Ronin attached power stone to his hammer and time stone was encased in the eye of agamotto. Moreover, all these stones could be wielded at the same time when they are attached to a gauntlet.
So, technically Tony’s power source is the Asgardian tech. Without that tech, neither arc reactor could be made nor it’s miniature version could have been created which powered the Iron-Man suit. Tony’s arc reactor was killing Junior Stark as it was volatile and unstable too. Tony then rediscovered the substitute to the palladium isotopes, which could power his suit just like palladium. The new element was more stable and posed less threat to his life.
Why Arc Reactor was originally Created?
It’s answer lies in the need to find a replacement for the non-renewable source of energy and the risky nuclear based energy. But as per the Iron-Man 2 tie-in comic Public Identity Howard had a bigger goal. He wanted to end the cold war and save the planet from eventual nuclear holocaust. He teamed up greatest mind of the planet and started the program “PROJECT UNITY”. Even Anton Vanko was part of it. But father of Ivan Vanko got greedy and he sold the project details to a outside party. Stark then got him deported back to Russia. However, continuing the project could risk leaking details of Howard’s other projects. So, the US government and him decided to end this program. Then arc reactor became his private property.
Eventually Tony used the reactor for the cause his father wanted ‘save the world’. When Stark junior perfected his model he made advanced Iron-Man suits which were helpful in saving the people in New York from the nuclear bomb and saving the universe from Thanos.