An institute in Japan says it has succeeded in forming a state of matter called "plasma," which plays a key role in nuclear fusion reactions. This could be a breakthrough toward achieving a next-generation energy source.

The National Institutes for Quantum Science and Technology made the announcement on Tuesday.

Nuclear fusion occurs inside the Sun's core. Making it happen artificially could lead to the production of massive amounts of energy.

It would be a next-generation energy source that emits no carbon dioxide and generates no high-level radioactive waste.

The institute says it succeeded in forming the "plasma" at a large-scale nuclear fusion experiment facility called JT-60SA, in Ibaraki Prefecture, north of Tokyo. The facility was jointly built by Japan and the European Union at a cost of more than 65 billion yen, or about 435 million dollars.

The facility is aimed at verifying technology that generates high-temperature and high-pressure "plasma," which is crucial in creating a nuclear fusion reaction and maintaining it for a certain period.

The institute says the facility started full-fledged operation in May. On Monday afternoon, it succeeded in forming "plasma" for the first time.

To achieve nuclear fusion, "plasma" needs to reach a temperature of more than 100 million degrees Celsius, and have nuclei collide at speeds of 1,000 kilometers per second.

The institute says that, at this point, scientists can only create a "plasma" temperature of 10 million degrees.

The institute aims to gain the technology necessary to maintain "plasma" at 100 million degrees Celsius for 100 seconds within about five years.

It says it wants to use the insights gained from the experiments for an international joint mega science project whose participants include Japan and the EU.

It also wants to realize nuclear fusion power generation, which the Japanese government aims to realize by around 2050.