Helion has performed thousands of tests with their sixth prototype called Trenta. In 2021, Trenta reached 100 million degrees C, the temperature they could run a commercial reactor. Magnetic compression fields exceeded 10 T, ion temperatures surpassed 8 keV, and electron temperatures exceeded 1 keV. They reported ion densities up to 3 × 10^22 ions/m3 and confinement times of up to 0.5 ms.

7th prototype Polaris
Helion's seventh-generation prototype, Project Polaris was in development in 2021, with completion expected in 2024. The device was expected to increase the pulse rate from one pulse every 10 minutes to one pulse per second for short periods. This prototype is the first of its kind to be able to heat fusion plasma up to temperatures greater than 100 million degrees C. Polaris is 25% larger than Trenta to ensure that ions do not damage the vessel walls.

Helion's plan with Polaris is to try demonstrate net electricity from fusion. They plan to demonstrate helium-3 production through deuterium-deuterium fusion.