While there is a lot of attention on non-fossil-fuel sources these days such as solarand hydrogen, the true Holy Grail of alternative energy is nuclear fusion, which theoretically could produce an endless source of clean power. Because scientists would have to basically reproduce the conditions at the core of the sun to bring this atom-mashing technology to fruition though, it’s been a bit slow to evolve. Researchers at MIT however, have just passed an important milestone on the long path to a fusion future, placing plasma under what they say is the most pressure ever created in a fusion device.

In nuclear fusion, the nuclei of atoms are basically forced to join together despite their natural repellency. When they fuse, they release a tremendous amount of energy. How much? Well, it’s the process that keeps our sun churning, where molecules of hydrogen are fused together in its core to create helium.

To recreate controlled nuclear fusion on Earth (unlike the uncontrolled version involved in a hydrogen bomb), gas is first heated to super-hot temperatures to form plasma. The plasma is simultaneously placed under intense pressure with the goal of keeping it stable, and is contained by an electromagnetic field.

While machines known as tokamaks, such as China’s Experimental Advanced Superconducting Tokamak (EAST), have created the intense temperatures needed for fusion reactors before, MIT is claiming first place in having created pressures never before attained. Using a tokamak called the Alcator C-Mod, which has been in operation at MIT for 23 years, researchers were able to place plasma under pressure equaling 2.05 atmospheres, a 15 percent leap over the previous C-Mod record of 1.77 atmospheres that was set in 2005. The university says it expects the new record to hold for 15 years as long as a new device – such as the one proposed by MIT itself – isn’t built before then.

MIT says that the Alcator C-Mod can create a magnetic field up to 8 tesla strong, which is 160,000 times the Earth’s magnetic field. In this particular record-smashing experiment, the machine reached 5.7 tesla. It also was heated to more than 35 million degrees Celsius (about twice the temperature at the core of the sun), produced 300 trillion fusion reactions per second, and carried 1.4 million watts of power. All of that took place in a chamber of about 1 cubic meter, which MIT says is not much larger than a coat closet.

Due to defunding by the US government, the Alcator C-Mod has now been deactivated; it reached its new record on its final day of operation.

This video provides a 360-degree tour of the device, as well as more information on how it works.